Prasanna

Students can read Kerala SSLC Biology Board Model Paper March 2024 with Answers English Medium and Kerala SSLC Biology Previous Year Question Papers with Answers helps you to score more marks in your examinations.

Kerala Syllabus Class 10 Biology Board Model Paper March 2024 with Answers English Medium

Time: 1½ Hours
Total Score: 40

Instructions:

• The first 15 minutes is cool-off time.
• You may use the time to read the questions and plan your answers.
• Answer only based on instructions and questions given.
• Consider score and time while answering.

Answer any 5 from questions 1-6. One score each. (5 × 1 = 1)

Question 1.
Identify the relationship in A and fill in B. (1)
(A) Dormancy of embryo: Abscisic acid
(B) Fruit formation: _________________
Answer:
(B) Fruit formation: Auxin

Question 2.
Which of the given statements is related to the sympathetic system? (1)

• Part of the autonomous nervous system.
• Part of the central nervous system.
• Production of saliva increases.
• Glycogen is converted to glucose.

Answer:

• Part of the autonomous nervous system.
• Glycogen is converted to glucose.

Question 3.
The hybridization of two contrasting traits of the character seed colour is illustrated below. Which will be the recessive trait of the F1 generation? (1)

Answer:
Green Seed Colour

Question 4.
What evidence supports the hypothesis given below? (1)
“Life originated in some other planet in the universe and accidentally reached the Earth.”
Answer:
The organic substances identified in the meteors that fell on Earth.

Question 5.
Choose the correct combination from the following: (1)
(i) Planaria: Eye spot: Taste
(ii) Shark: Jacobson’s organ: Smell
(iii) Snake: Lateral line: Body Balance
(iv) Housefly: Ommatidia: Light
(a) (i), (ii) correct.
(b) (ii) correct.
(c) (ii), (iii) correct.
(d) (iv) correct.
Answer:
(d) (iv) correct.

Question 6.
Correct the mistakes if any in the underlined part of the given statements.
(a) The complete genetic material present in an organism is called its genome.
(b) Gene mapping helps to identify the location of a particular gene in the DNA.
(c) The technology of testing the arrangement of nucleotides is gene therapy.
(d) Interferons are the proteins used for the treatment of viral diseases.
Answer:
(c) DNA Profiling (DNA Fingerprinting/DNA testing)

Answer any 6 from the questions 7-13. 2 scores each. (6 × 2 = 12)

Question 7.
Observe the illustration and answer the questions.
Organisms with variations

(a) Which theory of evolution is indicated here? (1)
(b) What is the significance of variations in the origin of new species according to this theory? (1)
Answer:
(a) Theory of Natural Selection (Darwin’s theory of evolution/Darwinism)
(b) Those with favorable variations survive in the struggle for existence. Variations that are inherited through generations and repeated differently, help to form species different from their ancestors.

Question 8.
Read the following statement and answer the question. (2)
‘The middle ear is separated from the external ear by the tympanum, air cannot pass through it’.
So how is the air pressure on either side of the tympanum regulated?
Answer:
The Eustachian tube helps to maintain a balance of air pressure on either side of the tympanum.

Question 9.
Observe the figures X and Y and answer the questions.

(a) Which neuron is present in abundance in the grey matter? What features did you consider for the selection? (1)
(b) In which neuron is the speed of impulse high? Why? (1)
Answer:
(a) Y, non-myelinated nerve cells are present in abundance is called grey matter.
(b) X, Myelinated axons transmit impulses much faster than other neurons.

Question 10.
Analyze the given condition and answer the questions:
‘Red blood cells bend like sickle’.
(a) Identify the disease. (1)
(b) In this condition, other blood cells do not undergo the same structural change as red blood cells. Why? (1)
Answer:
(a) Sickle cell anemia
(b) Because there is no hemoglobin in other blood cells. The defect in genes can cause deformities in the sequencing of amino acids, which are the building blocks of hemoglobin in Red blood cells.

Question 11.
Observe the illustration related to the sense of vision and answer the questions.

(a) Why is this type of image formed in the retina? (1)
(b) Even though such an image is formed, how can we see the object in its true form? (1)
Answer:
(a) Because the eye lens is a convex lens (Change in the curvature of the cornea and lens).
(b) The visual area of the brain (cerebrum) forms a correct image of the object. Then we can see the object in its true form.

Question 12.
Analyze the given illustration of the diseases and answer the questions.

(a) Complete ‘i’.
(b) Complete ‘ii’ and ‘iii’ choosing the appropriate one from the given diseases. (1)
Answer:
(a) (i) Viral Diseases
(b) (ii) Mosaic diseases
(iii) Hepatitis

Question 13.
Observe the poster against color discrimination and answer the questions.

(a) Name the pigment mentioned in the poster. (1)
(b) What is the reason for the rise and fall in the production of this pigment? (1)
Answer:
(a) Melanin
(b) Differences in the function of alleles of genes responsible for skin colour, is responsible for the rise and fall in the production of melanin.

Answer any 5 from questions 14-20. 3 scores each. (5 × 3 = 15)

Question 14.
Choose any one of the evidence given below and explain how it substantiates evolution.
(a) Palaeontology
(b) Physiology and Biochemistry
Answer:
(a) Primitive fossils have simple structures.
Recently formed fossils have complex structures.
Certain fossils are connecting links between different species.
Or
(b) Enzymes control chemical reactions
Energy is stored in ATP molecules.
Genes determine hereditary traits. / Carbohydrates, proteins, and fats are the basic substances.
All these give evidence that there was a common ancestor for all living organisms.

Question 15.
The opinions of three students on protein synthesis are given below. Analyze it and answer the question.

Student 1	Protein synthesis begins in the cytoplasm and ends in the nucleus.
Student 2	Protein synthesis begins in the nucleus and ends in the cytoplasm.
Student 3	The entire process of protein synthesis takes place in the nucleus.

Whose opinion is correct? Explain why? (3)
Answer:
(a) Student 2
The types of protein to be produced are determined by the gene of DNA in the nucleus. DNA does not participate directly in protein synthesis. So, an mRNA is formed from the DNA inside the nucleus. The functional mRNA from the nucleus is then transported to the cytoplasm of the cell for protein synthesis. Ribosomes are the protein factories that are present in the cytoplasm of the cell along with the tRNA, which contributes to protein synthesis in the cytoplasm.

Question 16.
Prepare a flow chart related to the sense of taste by selecting the appropriate information given in the box. (3)

Stimulate the olfactory receptors. Substances responsible for taste dissolve in saliva. Impulses reach the cerebrum. Aromatic particles enter the nostrils. Generate impulses. Enter in the taste buds. Experience taste. Stimulate the chemoreceptors. Aromatic particles dissolve in the mucus. Impulses reach the cerebellum.

Answer:
Substances responsible for taste dissolve in the saliva → Enter in the taste bud → Stimulate the chemoreceptors → Generate impulses → Impulses reach cerebrum → Experience taste.

Question 17.
Some of the defense mechanisms in plants are given below: (3)
(a) Callose
(b) Cuticle
(c) Bark
How do each of them help in defense?
Answer:
(a) Callose prevents germs that have crossed the cell wall from entering the cell membrane.
(b) Cuticle prevent the entry of germs through leaves.
(c) Bark protects the inner cells from direct contact with pathogens.

Question 18.
Rearrange columns B and C by column A: (3)

A. Disease	B. Pathogen	C. Spreading
Filariasis	Protozoa	Through Contact
Ringworm	Virus	Through Culex Mosquito
Malaria	Fungus	Through Air
	Bacteria	Through Female Anopheles Mosquito

Answer:

A. Disease	B. Pathogen	C. Spreading
Filariasis	Filarial Worms	Through Culex Mosquito
Ringworm	Fungus	Through Contact
Malaria	Protozoa	Female Anopheles Mosquito

Question 19.
Analyse the illustration and answer the questions:

(a) Which chemical is indicated as X?
(b) Fill in (i), (ii), (iii), and (iv).
Answer:
(a) X: Pheromones
(b) (i) Civetone
(ii) Muscone
(iii) Informing the availability of food
(iv) Determining the path of travel. (Any two)

Question 20.
Analyze the steps in the production of human insulin through genetic engineering and answer the questions.

• Step 1. Cutting of insulin gene from human DNA.
• Step 2. Joining insulin gene with plasmid.
• Step 3. A plasmid with a ligated insulin gene is inserted into the bacterial cell.
• Step 4. Bacteria multiply in the culture medium.

(a) Which are the enzymes used in steps 1 and 2? (1)
(b) What is the role of plasmid in this process? (1)
(c) Whether the succeeding generations of this bacterium can produce insulin. Why? (1)
Answer:
(a) Step 1: Restriction Endonuclease (Genetic Scissors)
Step 2: Ligase (Genetic Glue)
(b) A gene from one cell is transferred to another cell.
(c) Yes. The human insulin gene becomes part of the bacterial gene.
They carry the gene responsible for insulin production in their DNA.

Answer any 2 from questions 21-23. 4 Scores each. (2 × 4 = 8)

Question 21.
Analyze the table and answer the questions:

Person	Blood Group	Antigens	Antibodies
X	(i) _______	B, D	(ii) _______
Y	O-ve	(iii) _______	(iv) _______

(a) Fill in (i), (ii), (iii), and (iv). (2)
(b) Can person Y receive blood from person X? Why? (2)
Answer:
(a) (i) B +ve
(ii) a
(iii) Nil
(iv) a, b
(b) No – Blood does to match B & D antigen in the donor (X) blood and the antibodies a and b in the recipient (Y) blood will react with each other. This results in the clotting of blood. So, that person Y, can not receive blood from person X.

Question 22.
Redraw the diagram. Identify and label the parts mentioned below.

Redraw the diagram.
(a) Part that controls involuntary actions. (1)
(b) Part that evokes sensations. (1)
(c) Part that receives impulses from the vestibular nerve. (1)
Answer:
(a) Medulla Oblongata
(b) Cerebrum
(c) Cerebellum

Question 23.
Observe the illustration showing hormone action in cells X and Y and answer the questions.

(a) Identify the target cell of the hormone indicated. Why? (1)
(b) How do hormones change cellular activities? (1)
(c) What is the role of the hypothalamus in regulating the production of hormones? (2)
Answer:
(a) X, The specific receptors of hormone present in X cell.
(b) The hormone molecules bind with the respective receptor to form a hormone-receptor complex on the target cell. Then, the enzymes in the cells are activated within them and create changes in cellular activities.
(c) The hypothalamus secretes both releasing hormones and inhibitory hormones.
The releasing hormones secreted by the hypothalamus stimulate the pituitary glands to produce tropic hormones, which in turn will stimulate the different endocrine glands to produce their corresponding hormones.
The hypothalamus produces inhibitory hormones which inhibit the secretions of tropic hormone by the combined action of these two hormones, most of the endocrine glands are properly regulated.

Students can read Kerala SSLC Biology Question Paper March 2021 with Answers English Medium and Kerala SSLC Biology Previous Year Question Papers with Answers helps you to score more marks in your examinations.

Kerala Syllabus Class 10 Biology Question Paper March 2021 with Answers English Medium

Time: 1½ Hours
Total Score: 40

Instructions:

• 20 minutes is given as cool oft time.
• Use cool-off time to read the questions and plan your answers.
• Attempt the questions according to the instructions.
• Keep in mind, the score and time while answering the questions.
• The maximum score for questions from 1 to 36 will be 40.

1 score for each question from 1 to 10.

Question 1.
Complete the illustration according to the Model. (1)

Answer:
Deoxyribose Sugar

Question 2.
The blood group without antibodies is: (1)
(a) A
(b) B
(c) AB
(d) O
Answer:
(c) AB

Question 3.
Identify the part of the brain which helps to maintain homeostasis. (1)
(a) Cerebrum
(b) Thalamus
(c) Medulla oblongata
(d) Hypothalamus
Answer:
(c) Hypothalamus

Question 4.
Choose the correct pair. (1)
(a) Prolactin: Production of milk
(b) Aldosterone: Promotes growth
(c) Cortisol: Salt-water balance
(d) Melatonin: Maintains blood pressure
Answer:
(a) Prolactin: Production of Milk

Question 5.
The protein produced through genetic engineering which is used against viral diseases: (1)
(a) Insulin
(b) Interferons
(c) Endorphin
(d) Somatotropin
Answer:
(b) Interferons

Question 6.
Identify the word pair relation and fill in the blank. (1)
Genetic Scissors: Restriction Endonuclease
Genetic Glue: _____________
Answer:
Genetic Glue: Ligase

Question 7.
Which of the following statements is true about the yellow spot? (1)
(a) There is no vision at this point.
(b) Photoreceptors are absent here.
(c) The optic nerve begins from this point.
(d) This is the point of maximum visual clarity.
Answer:
(d) This is the point of maximum visual clarity.

Question 8.
Which is known as youth hormone. (1)
(a) Adrenaline
(b) Thymosin
(c) Aldosterone
(d) Testosterone
Answer:
(b) Thymosin

Question 9.
Identify the protozoal disease. (1)
(a) Malaria
(b) AIDS
(c) Rat fever
(d) Nipah
Answer:
(a) Malaria

Question 10.
Which organism belongs to cercopithecoidea? (1)
(a) Gorilla
(b) Gibbon
(c) Monkey
(d) Chimpanzee
Answer:
(c) Monkey

2 scores for each question from 11 to 22.

Question 11.
Skin is considered as the safety shield of the body. Why? (2)
Answer:
The outer epidermis of the skin contains a protein called keratin, which prevents germs from entering it. Sebum, produced by the sebaceous glands, makes skin oily and waterproof. Sweat, produced by the sweat glands, contains disinfectants to destroy germs. Skin also contains useful bacteria, which indirectly prevent germs.

Question 12.
Correct mistakes if any in the underlined part of given statements. (2)
(a) Substances responsible for taste should dissolve in mucus to stimulate the chemoreceptors.
(b) The cochlea contains specialized sensory hair cells concerned with hearing.
(c) Colour blindness is a condition caused by a defect in the cone cells.
(d) The cluster of photoreceptors of a housefly is the eye spot.
Answer:
(a) Saliva
(d) Ommatidia

Question 13.
What is the role of mRNA and tRNA in protein synthesis? (2)
Answer:

• mRNA carries information from DNA to ribosomes.
• tRNA carries various amino acids to ribosomes.

Question 14.
Complete the following table appropriately. (2)

Symptoms	Causes	Disease
(i)	Production of dopamine in the brain gets reduced.	(iii)
Loss of memory and inability to do routine work.	(ii)	(iv)

Answer:
(i) Loss of body balance. Tremor in muscles, flow of saliva.
(ii) Continuous degeneration of neurons due to accumulating an insoluble protein.
(iii) Parkinson’s
(iv) Alzheimer’s

Question 15.
We withdraw our hands when accidentally touch a sharp object. (2)
(a) What kind of response is mentioned here?
(b) Name two types of such responses.
Answer:
(a) Reflex Action
(b) Cerebral Reflex, Spinal Reflex

Question 16.
An illustration related to chemical evolution is given below. Complete it appropriately. (2)

Answer:
(i) Nitrogen Bases, Amino Acids, Fatty Acids
(ii) Nucleotide, Protein, Lipids
(iii) Primitive Cells

Question 17.
Name the secretions that defend pathogens in the following body parts. (2)
(a) Ear
(b) Stomach
(c) Trachea
(d) Urinary tract
Answer:
(a) Ear – Ear Wax
(b) Stomach – Hydrochloric Acid
(c) Trachea – Mucus
(d) Urinary Tract – Lysozyme

Question 18.
Complete Column B of the given table using the suitable functions given in the box. (2)

A. Plant Hormones	B. Functions
(a) Gibberellin	(i) _________________
(b) Auxin	(ii) _________________
(c) Abscisic acid	(iii) _________________
(d) Abscisic acid and Ethylene	(iv) _________________

• Dropping of leaves and fruits
• Sprouting of leaves
• Fruit Formation
• Dormancy of Embryo

Answer:

A. Plant Hormones	B. Functions
(a) Gibberellin	(i) Sprouting of Leaves
(b) Auxin	(ii) Fruit Formation
(c) Abscisic Acid	(iii) Dormancy of Embryo
(d) Abscisic Acid and Ethylene	(iv) Dropping of Leaves and Fruits

Question 19.
Write any two uses of DNA fingerprinting technology. (2)
Answer:

• To find out hereditary characteristics.
• To identify real parents in the case of parental dispute.
• To identify persons found after a long period of missing due to war or natural calamities.
• To find the real culprit to prove murder, robbery, etc.

Question 20.
Complete the table including the name of endocrine glands and their hormones responsible for the balance of Calcium levels in blood. (2)

Calcium Level in Blood	Hormone	Gland
(a) Increase	(i)	(ii)
(b) Decreases	(iii)	(iv)

Answer:

Calcium Level in Blood	Hormone	Gland
(a) Increase	(i) Calcitonin	(ii) Thyroid
(b) Decreases	(iii) Parathormone	(iv) Parathyroid

Question 21.
Observe the picture and answer the questions given below.

(a) Identify the photoreceptor.
(b) Name the pigment present in this receptor.
(c) Write the function of this pigment.
(d) Name the eye defect caused due to the deficiency of this pigment.
Answer:
(a) Rod Cell
(b) Rhodopsin
(c) Vision under dim light
(d) The deficiency of Vitamin A causes Night blindness

Question 22.
Analyze the illustration and answer the questions.

(a) Fill up (i) and (ii). (1)
(b) The chromosome of the father determines the sex of the child. Explain. (1)
Answer:
(a) (i) XX
(ii) XY
(b) The XY chromosomes of the father determine whether the child is male or female. The sex chromosomes of females are XX and males are XY. If the X chromosome in a male unites with the X chromosome in a female the offspring will be female (XX) and if the Y chromosome in a male unites with the X chromosome in a female, the offspring will be male (XY).

3 scores for each question from 23 to 32.

Question 23.
Observe the illustration and answer the questions.

(a) Identify the illustration. (1)
(b) What do A and B indicate? (1)
(c) Name the type of ‘B’ found only in DNA molecules. (1)
Answer:
(a) Nucleotide
(b) A: Sugar Molecule
B: Nitrogen Base
(c) Thymine

Question 24.
Read the statement and answer the questions.
‘Cancer is caused by the uncontrolled division of cells’.
(a) What is the reason for the uncontrolled division of cells? (1)
(b) Write any two factors causing cancer. (1)
(c) Suggest any two measures that reduce the chance of cancer. (1)
Answer:
(a) When the cell division mechanism fails, the normal cells get transformed into cancerous cells.
(b) Environmental factors, smoking, radiation, viruses, hereditary factors, etc.
(c) Avoid bad habits like consumption of alcohol, drug abuse; smoking, eat healthy food. Do exercise regularly, and maintain a healthy lifestyle.

Question 25.
Complete the following illustration using the appropriate statements given in the box. (2)

• Maintain equilibrium of the body Cerebellum.
• Evoke sensation.
• Centre of thought, intelligence, memory, and imagination.
• Thalamus.
• Analyses impulses from various parts of the body and sends to the cerebrum.

Answer:
(i) Cerebellum.
(ii) Maintain the equilibrium of the body.
(iii) Thalamus.
(iv) Centre of thought, intelligence, memory, and imagination.
(v) Evoke sensation.
(vi) Analyses impulses from various parts of the body and sends them to the cerebrum.

Question 26.
Analyse the given table and arrange Columns B and C according to Column A. (3)

A	B	C
Acromegaly	Increased production of somatotropin during the growth phase.	Overgrowth on the neck.
Cretinism	Excessive production of somatotropin after growth phase.	Excessive growth of the body.
Gigantism	Decreased production of thyroxine during infancy.	Overgrowth of bones on the face, jaws, and fingers.
	Excessive production of thyroxine.	Physical and mental growth retardation in children.

Answer:

A	B	C
Acromegaly	Excessive production of somatotropin after growth phase.	Overgrowth of bones on the face, jaws, and fingers.
Cretinism	Decreased production of thyroxine during infancy.	Physical and mental growth retardation in children.
Gigantism	Increased production of somatotropin during the growth phase.	Excessive growth of the body.

Question 27.
Complete the flow chart related to hearing by adding missing terms. (3)

Answer:
(i) Auditory canal
(ii) Eardrum
(iii) Ear ossicles
(iv) Cochlea
(v) Auditory nerve
(vi) Cerebrum

Question 28.
AIDS is a dreadful disease caused by HIV.
(a) Which cells in the human body are affected by HIV? (1)
(b) Write any two ways by which HIV is transmitted. (2)
Answer:
(a) Lymphocytes
(b) Through sexual contact with HIV infected person.
From HIV-infected mother to fetus.
By sharing needles and syringes contaminated with HIV components.
Through the reception of blood and organs contaminated with HIV.

Question 29.
Processes in the sense of sight are given below. Arrange them in sequential order. (3)

• Sense of sight.
• The lens focuses the light rays into the retina.
• The cornea refracts light into the eye.
• Impulse is transmitted through the optic nerve to the cerebrum.
• Photosensory cells on the retina are stimulated.
• Light enters through the pupil and falls on the lens.

Answer:

• The cornea refracts light to the eye.
• Light enters through the pupil and falls on the lens.
• The lens focuses on the light rays to the retina.
• Photosensory cells in the retina are stimulated.
• Impulse is transmitted through the optic nerve to the cerebrum.
• Sense of light.

Question 30.
Observe the News given below and answer the questions.

(a) What are vaccines? (1)
(b) Write any two components used in vaccines. (1)
(c) Name any two vaccines. (1)
Answer:
(a) Vaccines are substances, given in advance to prevent certain diseases they are used for artificial immunization.
(b) Dead, inactive, alive but neutralized germs, components of cellular parts of pathogens are used as vaccines.
(c) BCG, OPV, Pentavalent, MMR, TT.

Question 31.
Analyze the illustration and answer the questions.

(a) Fill up (i). (1)
(b) How does Natural Selection lead to the origin of new species? (2)
Answer:
(i) Struggle for existence.
(ii) When overproduction of organisms occurs, they compete for food, space, mates, and other limited resources (struggle for existence). In this struggle, only organisms with favorable variations survive in that nature. Over a long period, favorable variations accumulate, resulting in the formation of new species. (Natural selection).

Question 32.
Analyze the illustration and answer the questions given below:

(a) Identify the process illustrated here. (1)
(b) Name two white blood cells performing this function. (1)
(c) What is the importance of this process? (1)
Answer:
(a) Phagocytosis.
(b) Monocytes and neutrophils.
(c) Engulfing and destroying germs.

4 scores for each question from 33 to 36.

Question 33.
Observe the figure and answer the questions.

(a) Identify the cell. (1)
(b) Name the parts labeled A and B. (2)
(c) Write down the function of C. (1)
Answer:
(a) Neuron
(b) A: Dendron
B: Axon

(c) Secretes neurotransmitters, which stimulate the adjacent dendrite or cell and new electric impulses are generated.

Question 34.
Observe the illustration and answer the questions.

(a) Identify (i) and (ii). (1)
(b) Write two functions of (ii). (2)
(c) Name the condition resulting from the deficiency of (ii). (1)
Answer:
(a) (i) beta cells
(ii) Insulin
(b) It accelerates the process of glucose intake by the cells and the conversion of the excess glucose into glycogen.
(c) Diabetes.

Question 35.
‘BCG is the vaccine used against this disease’.
(a) Which disease is mentioned here? (1)
(b) How is this disease transmitted from one person to another? (1)
(c) Name the bacteria causing this disease. (1)
(d) Write any two organs affected by this disease. (1)
Answer:
(a) Tuberculosis.
(b) When the patient speaks, coughs, or sneezes, the pathogens spread into the air, and thereby to others.
(c) Mycobacterium tuberculosis.
(d) Lugs, kidneys, bones, joints, brain.

Question 36.
Redraw the figure. Identify, name, and label the following parts.

Redrawing diagram. (1)
(a) The projected transparent anterior part of the sclera. (1)
(b) The aperture is seen at the center of the iris. (1)
(c) The nerve that transmits impulses to the brain. (1)
Answer:

Students rely on Kerala Syllabus 9th Standard Chemistry Textbook Solutions Chapter 5 Chemical Kinetics Notes Questions and Answers English Medium to help self-study at home.

Kerala SCERT Class 9 Chemistry Chapter 5 Solutions Chemical Kinetics

Kerala Syllabus Std 9 Chemistry Chapter 5 Chemical Kinetics Notes Solutions Questions and Answers

Class 9 Chemistry Chapter 5 Let Us Assess Answers Chemical Kinetics

Question 1.
Classify the following chemical reactions into combination reaction, decomposition reaction, double decomposition reaction and displacement reaction.
Zn + FeSCO₄ → ZnSO₄ + Fe
NaCl + AgNO₃ → NaNO₃ + AgCl
2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂
H₂ + I₂ → 2HI
Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃
NH₄NO₂ → 2H₂O + N₂

Answer:

Question 2.
Write the balanced chemical equations of the chemical reactions given below and classify them into combination reactions, decomposition reactions and displacement reactions.
a. Magnesium + Nitrogen → Magnesium nitride
b. Zinc carbonate \(\xrightarrow{\text { Heat }}\) Zinc oxide + Carbon dioxide
c. Aluminum + Lead nitrate → Aluminum nitrate + Lead
Answer:
a. 3Mg + N₂ → Mg₃N₂ [Combination reaction]
b. 2ZnCO₃ → 2ZnO + 2CO₂ [ Decomposition Reaction]
c. 2Al + 3Pb(NO₃)₂ → 2Al(NO₃)₃ + 3Pb [Displacement Reaction]

Question 3.
Identify the types of chemical reactions given below.
i. Formation of black copper oxide on heating copper powder in a China dish
ii. Silver nitrate solution reacts with sodium chloride solution to form silver chloride and sodium nitrate solution.
iii. Formation of ferric oxide, Sulphur dioxide and Sulphur trioxide on heating ferrous sulphate granules in a test tube.
Answer:
i. Combination Reaction
Copper (Cu) combines with oxygen (O₂) from the air to form copper (II) oxide (CuO).

ii. Double Displacement Reaction
The silver ions (Ag⁺) and chloride ions (Cl^–) exchange take place, forming silver chloride (AgCl) and sodium nitrate (NaNO₃).

iii. Decomposition Reaction
Ferrous sulphate (FeSO₄) decomposes upon heating to form ferric oxide (Fe₂O₃), sulphur dioxide (SO₂), and sulphur trioxide (SO₃).

Question 4.
What are displacement reactions? Write an example
Answer:
Displacement reactions are chemical reactions where one element or ion is replaced by another in a compound.
Zn + CuSO₄ → ZnSO₄ + Cu
In this reaction, zinc (Zn) displaces copper (Cu) from copper sulphate (CuSO₄), resulting in the formation of zinc sulphate (ZnSO₄) and copper.

Question 5.
Write two examples each of chemical reactions that take days or months to complete and those that take just a few seconds or minutes.
Answer:
Reactions That Take Days or Months to Complete:

• Rusting of Iron:
  Iron reacts with oxygen and moisture oVer time to form iron oxide (rust). This process can take days to years, depending on environmental conditions.
• Fermentation:
  The fermentation of sugars by yeast to produce alcohol (ethanol) can take several days to weeks. For example, in winemaking, the process typically lasts from a few days to several weeks.

Reactions That Take Just a Few Seconds or Minutes:

• Combustion of a Fuel:
  The burning of gasoline in an engine occurs very quickly, usually in seconds. For example, igniting a lighter or a matchstick produces a flame almost instantaneously.
• Neutralisation Reaction:
  The reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH) to form sodium chloride (NaCl) and water (H₂O) is rapid, often completing within minutes.

Question 6.
How does the rate of a chemical reaction vary when a gas reacts with large pieces of a solid substance and its fine powder? Explain the reason.
Answer:
The rate of a chemical reaction depends on the surface area.

Large Pieces of Solid:
Only the outer surface reacts with the gas, which slows down the reaction because there’s less area for the gas to interact with.

Fine Powder:
The fine powder has a much larger surface area, allowing more gas molecules to collide with it at once. This speeds up the reaction.
The surface area of a reactant significantly affects the rate of a chemical reaction. A larger surface area leads to more frequent collisions between reactant molecules, which, in turn, increases the rate of the reaction.

Question 7.
The rate of a chemical reaction for a fixed amount of a reactant is slow at room temperature.
Is it possible to increase the rate of the chemical reaction without changing the temperature? Explain.
Answer:
Yes, it is possible to increase the rate of a chemical reaction without changing the temperature. Here are a few methods to achieve this:

• Increase Surface Area
• Increase Concentration
• Stirring of Agitation
• Use of Catalysts

These methods can enhance the reaction rate without raising the temperature.

Question 8.
Zinc reacts with hydrochloric acid to produce hydrogen gas.
a. Write the chemical equation of this reaction.
b. What type of chemical reaction is this?
c. Suggest any two methods for increasing the amount of hydrogen.
Answer:
a. Zn + 2HCl → ZnCl₂ + H₂

b. This is a displacement reaction because zinc displaces hydrogen from hydrochloric acid.

c. Increase the Concentration of Hydrochloric Acid:
Using a more concentrated solution of hydrochloric acid increases the availability of H⁺ ions, leading to more frequent collisions and a higher rate of hydrogen gas production.

Increase the Surface Area of Zinc:
Using zinc in the form of a fine powder instead of larger pieces will increase the surface area, allowing more collisions with hydrochloric acid and producing more hydrogen gas.

Question 9.
The chemical equation of the conversion of hydrogen peroxide to water and oxygen is given.
2H₂O₂ → 2H₂O + O₂
a. What type of chemical reaction is this?
b. Which substance is used to accelerate the decomposition of H₂O₂? By what name is it commonly known?
Answer:
a. This is a decomposition reaction. In this type of reaction, a single compound (hydrogen peroxide) breaks down into two or more products (water and oxygen).

b. The substance commonly used to accelerate the decomposition of hydrogen peroxide is manganese dioxide (MnO₂). It is often referred to simply as a catalyst. Catalysts speed up chemical reactions without being consumed in the process.

Question 10.
Solutions of ammonium chloride and sodium hydroxide are taken in a test tube and heated.
a. Which gas is produced?
b. Which factor helps to increase the rate of the chemical reaction?
c. What is threshold energy?
d. Why does the rate of a chemical reaction increase as temperature increases?
Answer:
a. When solutions of ammonium chloride (NH₄Cl) and sodium hydroxide (NaOH) are heated, ammonia gas (NH₃) is produced along with water and sodium chloride (NaCl). The reaction can be represented as follows:
NH₄Cl + NaOH → NH₃(g) + H₂O + NaCl

b. One factor that helps to increase the rate of this chemical reaction is increasing the temperature. Heating the reactants speeds up the movement of particles, leading to more frequent and energetic collisions.

c. Threshold energy, also known as activation energy, is the minimum amount of energy required for reactants to undergo a chemical reaction. Only particles with energy equal to or greater than this threshold can effectively collide and react to form products.

d. The rate of a chemical reaction increases as temperature increases because:

• Increased Kinetic Energy: Higher temperatures give reactant particles more kinetic energy, causing them to move faster.
• More Frequent Collisions: Faster-moving particles collide more often, which increases the rate of successful collisions.
• Greater Energy of Collisions: Increased temperature means that a greater proportion of the particles have energy equal to or greater than the threshold energy, leading to more reactions occurring.

Extended Activities

Question 1.
Carry out the reaction between dilute hydrochloric acid and magnesium, following the experimental procedure given below.

Take 25 mL of dilute HCl in a conical flask. Place a 15 cm long Mg ribbon in the flask and start a stopwatch. Record the volume of hydrogen gas produced every 30 seconds, Swirl the flask slowly at regular intervals to ensure continuous reaction of the reactants. After fhe experiment, plot a graph between the volume of hydrogen on the ‘Y’ axis and time on the ‘X’ axis.

i. When is the rate of the chemical reaction highest in this experiment?
ii. How can the variation in the rate of the chemical reaction be explained?
iii. Repeat the above experiment using 25 mL of concentrated HCl instead of dilute HCl. Draw the graph. What change is noticed in the rate of the chemical reaction?
iv. Repeat the experiment by placing a 5 cm long Mg ribbon in 25 mL hydrochloric acid. Then, repeat the experiment by replacing the Mg ribbon with magnesium powder of equal mass. Compare the rates of chemical reactions using the graph.
v. Heat the system to 50°C. Then, put a 5 cm long Mg ribbon and record the volume of hydrogen every 30 seconds. Explain how the change in temperature affects the rate of chemical reaction by plotting the graph.
Answer:
i. The rate of the reaction is highest at the beginning when magnesium is freshly exposed to the acid.
Initially, the surface area available for reaction is maximised, and both reactants are at their highest concentrations.

ii. The rate decreases over time as:

• The concentration of HCl decreases as it reacts with Mg.
• The magnesium surface may become coated with magnesium chloride, hindering further reaction.
• The reaction is exothermic, but the initial conditions and reactant concentrations have the most impact on the rate.

iii. When using concentrated HCl:

• The rate of hydrogen gas production will increase significantly.
• The graph will show a steeper initial slope compared to the dilute HCl graph due to a higher concentration of HCl leading to more frequent collisions between reactant molecules.

iv. 5 cm Mg ribbon: The surface area is less than that of the magnesium powder, resulting in a slower reaction rate. The graph will show a lower rate of hydrogen production.
Magnesium powder: This increases the surface area exposed to the acid, leading to a rapid reaction and a steeper slope in the graph compared to the ribbon. The volume of hydrogen gas produced over time will be greater with the powder.

Comparing two reactions – the greater the surface area, the greater the rate of reaction.
v. Heating the system to 50°C increases the kinetic energy of the molecules, resulting in more frequent and effective collisions.
You would observe an increased volume of hydrogen gas produced over time, reflected in a steeper slope on the graph compared to the reaction at room temperature.

Comparing two reactions – the higher the temperature, the greater the rate of reaction.

Question 2.
Take an equal volume of potassium persulphate (K₂S₂O₈) solution in two test tubes. Heat one of the test tubes. Pour an equal amount of potassium iodide solution into both the test tubes.
a. In which test tube does iodine precipitate rapidly and form a brown colour?
b. Write the chemical equation of this reaction.
c. What is the effect on the rate of reaction by adding a little manganese dioxide to the unheated test tube?
d. What is the role of manganese dioxide here?
Answer:
a. Iodine precipitates rapidly and forms a brown colour in the test tube that was heated. Heating increases the reaction rate due to higher kinetic energy, leading to more frequent and effective collisions between reactants.

b. The reaction can be represented as follows
2KI + K₂S₂O₈ → 2K₂SO₄ + I₂

c. Adding manganese dioxide (MnO₂) to the unheated test tube increases the rate of reaction. MnO₂ acts as a catalyst, speeding up the formation of iodine without being consumed in the reaction.

d. Manganese dioxide acts as a catalyst in this reaction. It provides an alternative pathway with a lower activation energy, allowing the reaction to proceed more quickly, even at lower temperatures. This results in a more rapid formation of iodine, contributing to a more pronounced brown colour in the solution.

Question 3.
Observe the rate of formation of hydrogen iodide by passing a fixed amount of hydrogen gas at room temperature into the iodine crystal taken in a closed container. Repeat this experiment by heating up to 130°C. What change occurs in the rate of the chemical reaction? Explain.
Answer:
At Room Temperature:
Rate of Reaction: The reaction will proceed but at a relatively slow rate due to the lower kinetic energy of the molecules. The collisions between hydrogen and iodine molecules will happen less frequently and with less energy, resulting in a gradual formation of hydrogen iodide.

At 130°C:
Rate of Reaction: When the temperature is raised to 130°C, the rate of formation of hydrogen iodide significantly increases. This is due to the following reasons:

• Increased Kinetic Energy: Heating the system increases the kinetic energy of the reactant molecules, leading to more frequent and more energetic collisions.
• Higher Reaction Rates: The increased energy helps overcome the activation energy barrier more effectively, resulting in a faster reaction rate and more rapid formation of HI Heating the system to 130°C accelerates the reaction between hydrogen and iodine, resulting in a faster formation of hydrogen iodide compared to room temperature conditions.

Chemical Kinetics Class 9 Notes Questions and Answers Kerala Syllabus

Question 1.
Take some sugar (C₁₂H₂₂O₁₁) in a spatula and heat it on a bunsen burner.
What is the colour of the product obtained?
Answer:
Black
The product formed is carbon. On strong heating, sugar decomposes to form carbon and water.
C₁₂H₂₂O₁₁ + Heat → 12C + 11H₂O

Question 2.
Take some sodium carbonate (Na₂CO₃) in a test tube. Add 2 – 3 mL of dilute hydrochloric acid to it.
What is your observation?
Answer:
Brisk effervescence is observed, indicating the presence of CO₂ gas.
Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂

Question 3.
Add 2 – 3 mL of potassium iodide solution to 2 – 3 mL of lead acetate (Pb(CH₃COO₂) solution in a test tube.
a. In which part of the test tube is the product found?
Answer:
At the bottom as a precipitate.

b. What is its colour?
Answer:
Yellow
The product formed in yellow colour is lead iodide.
Pb(CH₃-COO)₂ + 2KI → PbI₂ + K₂(CH₃-COO)₂

Question 4.
Take some iron sulphide of a test tube. Add 2 – 3 mL of dilute hydrochloric acid to it and heat, Is the smell familiar?
Answer:
When dilute hydrochloric acid is heated with iron sulphide, a gas is produced that smells like rotten eggs. This gas is hydrogen sulphide.
FeS + 2HCl → FeCl₂ + H₂S
Inferences of the activities given above

Experiment	How the chemical change is identified
1	The colour of the sugar changed
2	A gas is liberated
3	A precipitate is formed
4	A pungent gas is produced

Question 5.
What do you observe?
Answer:
The outer side of the beaker feels hot.
Here, calcium oxide reacts with water to form calcium hydroxide (Ca(OH)₂). It is an exothermic reaction as well.

Question 6.
Write the chemical equation of the reaction.
Answer:
CaO + H₂O → Ca(OH)₂ + heat
An exothermic reaction is a chemical reaction that releases heat.
Eg: Burning of fuel
Endothermic reactions are chemical reactions that involve the absorption of heat.
Eg: CaCO₃ + Heat → CaO + CO₂

Question 7.
Which are the substances combined in the following reactions? What are the products obtained as a result of these reactions?
a. N₂ + 3H₂ → 2NH₃
b. 2SO₂ + O₂ → 2SO₃
Answer:

Reaction	Substances combined	Products formed
a	N2, H2	NH3
b	2SO2, O2	SO3

The reaction in which two or more simple substances (elements/compounds) combine to* form a compound is called combination reaction.
More examples of combination reaction

• 2H₂ + O₂ → 2H₂O
• 2Na + Cl₂2 → 2NaCl
• C + O₂ → CO₂
• H₂ + Cl₂ → 2HCl
• 2Mg + O₂ → 2MgO
• S + O₂ → SO₂

Question 8.
What change is observed?
Answer:
Ammonium dichromate bums in a purple (pink) colour.
When ammonium dichromate undergoes thermal decomposition, chromium trioxide (Cr₂O₃), water vapour and nitrogen are formed.
(NH₄)₂Cr₂O₇ → Cr₂O₃ + 4H₂O + N₂↑

Question 9.
Examine the following chemical reactions.
a. 2Pb(NO₃)₂ → 2PbO + 4NO₂↑ + O₂↑
b. CaCO₃ → CaO + CO₂↑

Which substances underwent decomposition? What are the products obtained?
Answer:

Reaction	Substances that underwent decomposition	Products obtained
a	Pb(NO3)2	PbO, NO2, O2
b	CaCO3	CaO, CO2

Decomposition reaction is the process by which a compound breaks down into two or more substances

More examples of decomposition reaction

• 2HgO → 2Hg + O₂
• 2H₂O → 2H₂ + O₂
• C₁₂H₂₂O₁₁ → 12C + 11H₂O
• Ca(OH)₂ → CaO + H₂O
• 2HI → H₂ + I₂
• 2Al(OH)₃ → Al₂O₃ + 3H₂O
• NH₄Cl → NH₃ + HCl

Question 10.
Heat a small amount of copper carbonate (CuCO₃) in a boiling tube. What change is observed? What are the products obtained? Write the balanced chemical equation of the chemical reaction.
Answer:
CO₂ gas is produced. Blue copper carbonate turns into black-coloured cupric oxide.
CuCO₃ + Heat → CuO + CO₃

Question 11.
What do you observe?
Answer:
A white curdy precipitate is formed.

Question 12.
Examine the chemical equation of this reaction given below.
NaCl + AgNO₃ → AgCl↓ + NaNO₃
Can you identify the product precipitated as a result of this reaction?
Answer:
Silver chloride is the insoluble precipitate formed.
(Sodium nitrate is soluble in solution)

Question 13.
In one of the reactants, sodium chloride, which ion is bonded to the sodium ion?
Answer:
Chloride ion.

Question 14.
Among the products formed, with which metal ion does the chloride ion combine?
Answer:
Silver ion.

Question 15.
Consider the nitrate ion in the second reactant silver nitrate. With which metal ion does the nitrate ion combine to form the product?
Answer:
Sodium ion.
In the reaction between sodium chloride and silver nitrate, ions are exchanged.

Double decomposition reaction is a reaction in which two compounds, reacting with each other, interchange their ions to form two new compounds.

Double decomposition reactions can be classified into three types.
1. Precipitation reactions – Precipitates are insoluble solid compounds which can be separated from the solution.
MgCl₂ + H₂SO₄ → MgSO₄ + 2HCl

2. Reactions that involve formation of gas.
CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

3. Reactions that involve formation of products among which at least one compound does not dissociate into ions.
The neutralisation reaction between an acid and a metal hydroxide base to give water and salt is an example of such a chemical reaction.
HCl + NaOH → NaCl + H₂0

More examples of double decomposition reaction

• Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
• HCl + NaOH → NaCl + H₂O
• CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂
• MgCl₂ + H₂SO₄ → MgSO₄ + 2HCl
• 2NaCl + H₂SO₄ → Na₂SO₄ + 2HCl
• 2NaNO₃ + H₂SO₄ → Na₂SO₄ + 2HNO₃

Question 16.
What do you observe?
Answer:
The reaction bubbles vigorously as hydrogen gas is produced.

Question 17.
Which gas burns with a ‘pop’ sound?
Answer:
Hydrogen gas bums with a pop sound.

Question 18.
Notice the balanced chemical equation of this chemical reaction, given below.
Zn + 2HCl → ZnCl₂ + H₂↑
During this chemical reaction, which atom replaces hydrogen in the reactant, HCl, to form the product?
Answer:
The zinc atom replaces the hydrogen atom in hydrochloric acid.
Reactions in which an element in a compound is displaced by another element are called displacement reactions
More examples of displacement reactions

• Mg + 2HCl → MgCl₂ + H₂
• Zn + H₂SO₄ → ZnSO₄ + H₂
• CuSO₄ + Fe → FeSO₄ + Cu
• CuSO₄ + Zn → ZnSO₄ + Cu
• Fe₂O₃ + Al → 2Fe + Al₂O₃

Question 19.
Classify the following chemical reactions into combination reaction, decomposition reaction, double decomposition reaction and displacement reaction. Also, include more examples.
1. Zn + 2AgNO₃ → Zn(NO₃)₂ + 2Ag
2. CaCO₃ → CaO + CO₂
3. 2HI → H₂ + I₂
4. Cu(NO₃)₂ + Na₂S → CuS + 2NaNO₃
5. SO₂ + H₂O → H₂SO₃
Answer:
Combination reactions
SO₂ + H₂O → H₂SO₃
N₂ + 3H₂ → 2NH₃
2CO + O₂ → 2CO₂
NH₃ + HCl → NH₄Cl
2H₂ + O₂ → 2H₂O

Decomposition reactions
2HI → H₂ + I₂
CaCO₃ → CaO + CO₂
NH₄Cl → NH₃ + HCl
2H₂O → 2H₂ + O₂
CuCO₃ → CuO + CO₂

Double decomposition reactions
Cu(NO₃)₂ + Na₂S → CuS + 2NaNO₃
CuSO₄ + BaCl₂ → CuCl₂ + BaSO₄
Na₂SO₄ + BaCl₂ → 2NaCl + BaSO₄
Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃

Displacement reactions
Zn + 2AgNO₃ → Zn(NO₃)₂ + 2Ag
CuSO₄ + Fe → FeSO₄ + Cu
Zn + 2HCl → ZnCl₂ + H₂
Mg + H₂SO₄ → MgSO₄ + H₂

Question 20.
What measures do we take to prevent the spoilage of food?
Answer:

• Preserve using salt.
• Use of preservatives.
• Keep refrigerated.
• Sterilisation
• Dry storage

All chemical reactions do not take place at the same speed. There are several factors that affect the speed of a chemical reaction.

Question 21.
Take an equal volume of dilute hydrochloric acid in three test tubes. Place pieces of copper (Cu), zinc (Zn), and magnesium (Mg) of the same size in each of the three test tubes.
Observation:
Test tube 1: -No reaction
Test tube 2: – A moderate reaction will be observed with zinc. Gas evolution will be slower than with magnesium, and the metal will dissolve at a slower rate.
Test tube 3: – The most vigorous reaction will occur with magnesium. You will observe rapid gas evolution, and the metal will dissolve quickly.

a. Which test tube shows the highest rate of chemical reaction?
Answer:
Test tube 3
Here, since the metals are of the same size and the volume of hydrochloric acid is equal, it is clear that the rate of chemical reaction is different due to the characteristic properties of metals like copper, zinc and magnesium.

b. Why does magnesium react very slowly with water while sodium reacts vigorously with water at room temperature?
Answer:
The rate of chemical reaction depends on the nature of the reactants. Sodium is a more reactive metal than magnesium. So sodium reacts strongly with water even at normal temperature.

Question 22.
Take an equal volume of concentrated hydrochloric acid and dilute hydrochloric acid in two test tubes.
a. If so, which test tube contains a greater number of HCl molecules per unit volume?
Answer:
The test tube containing concentrated HCl contains a greater number of HCl molecules Place magnesium ribbons of equal mass in both test tubes.
Record the observation of the chemical reaction taking place in each test tube.

Test tube 1: – Vigorous reaction: Immediate and intense bubbling occurs.
Test tube 2: – Slower reaction: Bubbling is observed, but it is less intense than with concentrated HCl.

b. Which test tube shows the higher rate of a chemical reaction?
Test tube 1
Answer:

• Because the number of reactant molecules per unit volume is greater in a test tube containing concentrated hydrochloric acid.
• As the concentration of reactant increases, the number of particles per unit volume increases, and
  consequently, the number of effective collisions increases. Due to this, the rate of chemical reaction also increases.

Question 23.
If steel wool is heated in air, it will become red hot and get oxidised slowly. However, if the heated steel wool is exposed to an oxygen-rich environment, it will burn strongly and produce the product at a faster rate. What is the reason for this?
Answer:
This is due to the concentration of oxygen which is one of the properties. As the density increases, the number of effective collisions increases, and the rate of chemical reaction increases.

a. Which are the reactants in this chemical reaction?
Answer:
Piece of marble, Hydrochloric acid (HCl)

b. What are their physical states?
Answer:
Piece of marble: Solid state
Hydrochloric acid (HCl): Liquid
Let us write the chemical equation of this reaction.
CaCO₃(s) + 2HCl(l) → CaCl₂(s) + H2O(1) + CO(g)
Experiment:

Question 24.
Now, take a piece of marble and powdered marble of equal mass. Treat them with dilute hydrochloric acid of equal volume and same concentration. Record the observations.

a. Is the rate of the reaction the same in both the beakers?
Answer:
No

b. Is the surface area of the marble equal?
Ans:
No

c. What change occurs in the rate of collision between the reactant molecules as the surface area increases?
Answer:
The surface area of a reactant significantly affects the rate of a chemical reaction. A larger surface area leads to more frequent collisions between reactant molecules, which, in turn, increases the rate of the reaction.

d. What is the change in the rate of reaction if the marble pieces are ground to fine powder?
Answer:
If marble pieces are ground to fine powder, the rate of reaction will increase significantly. This is
because grinding the marble into a fine powder increases its surface area. With a larger surface area, there are more points of contact between the marble and the hydrochloric acid, leading to more frequent collisions between the reactant molecules. This increased collision rate results in a faster reaction.

Example: Wood bums quickly when it is cut into small pieces. The rate of chemical reaction increases with an increase in surface area.

Physical state of reactants and rate of reaction
The rate of a chemical reaction is related to the physical state of the reactants. When zinc sulphate and barium nitrate in a solid state are mixed, no noticeable reaction takes place between them. But when their aqueous solution is mixed, a white precipitate of barium sulphate is immediately formed. This chemical reaction occurs due to the effective collision between the molecules. That is, the physical state of the reactants plays an important role in determining the rate of reaction. This explains why gasoline vapour ignites more explosively than liquid gasoline.

Question 25.
Take dilute hydrochloric acid in two test tubes. Put a large piece of eggshell in the first test tube. In the second test tube, add an equal amount of powdered eggshell.

a. In which test tube is the rate of chemical reaction found to be higher?
Answer:
The rate of chemical reaction will be higher in the test tube containing powdered eggshell.

b. What is the reason for this?
Answer:
The reason for the faster reaction with powdered eggshell is increased surface area. When the eggshell is powdered, its surface area is significantly larger than that of a large piece. This increased surface area allows for more contact between the eggshell and the hydrochloric acid, leading to ‘ more frequent collisions between the reactant molecules and a faster reaction rate.

c. Write the chemical equation of the chemical reaction taking place here.
Answer:
The chemical reaction between eggshell (calcium carbonate, CaCO₃) and hydrochloric acid (HCl) produces calcium chloride (CaCl₂), water (H₂O), and carbon dioxide gas (CO₂). The balanced chemical equation is:
CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g)

Question 26.
Firecrackers used to enrich celebrations contain magnesium. Magnesium gives off a rich glow when it burns. Magnesium powder is used here. What could be the reason?
Answer:
Magnesium powder is used in firecrackers because it bums very brightly and produces a dazzling white light.

Here’s why:

• High reactivity: Magnesium is a highly reactive metal, meaning it readily reacts with oxygen in the air.
• Exothermic reaction: The reaction between magnesium and oxygen is highly exothermic, releasing a large amount of heat and light.
• Bright flame: The intense heat causes the magnesium to bum with a brilliant white flame.
• Fine powder: Using magnesium powder increases the surface area, which leads to a faster and more intense reaction, resulting in a brighter and more dazzling light.

Question 27.
Temperature is the measure of the hotness or coldness of a matter.
Let us examine the reaction between ammonium chloride (NH₄Cl) and sodium hydroxide (NaOH).
a. What are the products obtained when these compounds react?
Answer:
Sodium chloride (NaCl), Water (H₂O) and Ammonia gas (NH₃)
NH₄Cl + NaOH → NaCl + H₂O + NH₃↑
Experiment:
Take 2 mL of ammonium chloride solution in a test tube and pour into it 2 mL of sodium hydroxide solution taken in another test tube.

b. Did you observe the formation of any product?
Answer:
Yes

c. Wave your hand so that air from the mouth of the test tube moves towards your nose.
Do you experience any smell?
Answer:
A slight odour of ammonia.

d. Heat the test tube and check the smell again. Write your observation.
Answer:
The pungent smell of ammonia is obtained when the test tube is heated. That is, the increase in the rate of reaction is due to the increase in temperature.

Question 28.
The procedure for the chemical reaction between sodium thiosulphate (Na₂S₂O₃) and hydrochloric acid (HCl) is given below. Identify the factor that affects the rate of a chemical reaction by doing the experiment.
Prepare a dilute solution of sodium thiosulphate in a beaker. Take an equal amount of this solution in two test tubes. Heat one of the test tubes for a short while. Pour an equal volume of dilute hydrochloric acid into both test tubes.
Record your observations.
Answer:
Appearance of the cloudy precipitate.

a. In which test tube did the precipitate form quickly?
Answer:
The faster appearance of the cloudy precipitate in the heated test tube indicates that the reaction rate is higher at higher temperatures. This demonstrates that temperature is a factor that affects the rate of a chemical reaction.

b. Which factor influenced the rate of the chemical reaction here and write the chemical equation for the reaction involved.
Answer:
Temperature influences the rate of the chemical reaction.
The experiment showed that the heated test tube produced a cloudy precipitate more quickly than the one at room temperature. This indicates that increasing the temperature accelerated the reaction.
Na₂S₂O₃ + HCl → 2NaCl + S + H₂O + SO₂

Let us recognise the effect of temperature on some of the reactions around us,

• The dough that we grind to make dosa and idli can be seen to ferment quickly at normal temperature, but if the dough is kept in the refrigerator, it will rise slowly.
• You know that light worms can emit light by the chemiluminescence effect. Light sticks mixed with certain chemicals can also emit light. Such light sticks can emit intense light at high temperatures.

Question 29.
Take some hydrogen peroxide solution in a boiling tube. Insert a burning incense stick in the boiling tube.
Let us write the chemical equation of this reaction.
2H₂O₂ → 2H₂O + O₂ ↑
a. Is there any difference in the burning of the incense stick?
Answer:
When you insert a burning incense stick into a boiling tube containing hydrogen peroxide, you’ll likely observe a more vigorous and brighter flame compared to its burning in air alone.
Now, add a little manganese dioxide (MnO₂) into the boiling tube and insert the burning incense stick in the tube again.

b. What is observed now?
Answer:
It can be seen that the speed of combustion of the incense stick has increased. This is because the
rate of decomposition of hydrogen peroxide increases, and more oxygen is released.
Manganese dioxide is used as a catalyst in the decomposition of hydrogen peroxide. Here, the decomposition of hydrogen peroxide is accelerated by the substance manganese dioxide.

c. Can you identify the catalysts in the following chemical reaction
i. Manufacture of ammonia by Haber process.

Answer:
The catalyst used in the Haber process for the manufacture of ammonia is iron (Fe)

ii. Manufacture of sulphuric acid by contact process

Answer:
The catalyst used in the Contact Process is vanadium pentoxide (V₂O₅).

Catalysis in nature

• Enzymes are protein molecules that act as catalysts in living cells.
• They accelerate chemical reactions at normal temperature and pressure.
• Amylase is an example of an enzyme found in saliva.
• It converts starch into maltose.

Catalyst and Magic
Catalyst and Sugar Candy

• Sugar candy melts when heated but doesn’t bum.
• Adding ash to the suger candy before heating can cause it to bum.
• Metal compounds in the ash act as catalysts for the combustion of the sugar candy.

Bombardier Beetle Defense

• Bombardier beetles use catalytic decomposition of hydrogen peroxide for self-defence.
• Enzymes produced by the beetle accelerate this reaction, releasing steam and other irritating chemicals.

Students can read Kerala SSLC Biology Question Paper March 2022 with Answers English Medium and Kerala SSLC Biology Previous Year Question Papers with Answers helps you to score more marks in your examinations.

Kerala Syllabus Class 10 Biology Question Paper March 2022 with Answers English Medium

Time: 1½ Hours
Total Score: 40

Instructions:

• There is a ‘Cool-off time’ of 15 minutes in addition to the writing time.
• Use this time to get familiar with questions and to plan your answer.
• Questions with different scores are given as distinct parts.
• Read the instructions carefully before answering the questions.
• Keep in mind, the score and time while answering the questions.
• The maximum score for questions from 1 to 24 will be 40.

Part – I

(A) Answer any 4 questions from 1 to 6. Each carries 1 score. (4 × 1 = 4)

Question 1.
Identify the given photoreceptor cell.

Answer:
Cone Cell

Question 2.
If there is any mistake in the underlined part of the given statements, correct it.
(a) Chemical evolution theory was proposed bv Oparin and Haldane.
(b) Organic molecules such as Nucleic acids are formed in the Urey-Miller experiment.
Answer:
(b) Amino acids

Question 3.
Find the genetic constitution of the sperm.
(a) 44 + X
(b) 22 + XX
(c) 44 + XX
(d) 22 + Y
Answer:
(d) 22 + Y

Question 4.
Choose the correct pair.

• Dormancy of embryo: Cytokinin
• Sprouting of leaves: Abscisic acid
• Fruit formation: Gibberellin
• Ripening of leaves and fruits: Ethylene

Answer:
Ripening of Leaves and Fruits: Ethylene

(B) Answer all questions from 7 to 9. Each carries 1 score. (3 × 1 = 3)

Question 5.
Identify the blood group that has the following peculiarities.

Antigen A	Antigen B	Antigen D
Nil	Present	Nil

Answer:
B-ve

Question 6.
The vector used in genetic engineering is:
(a) Ligase
(b) Plasmid
(c) tRNA
(d) rRNA
Answer:
(b) Plasmid

Answer all questions from 7 to 9. Each carries 1 score. (3 × 1 = 3)

Question 7.
Identify the word pair relationship and fill in the blanks.
Housefly: Ommatidia
Planaria: ____________
Answer:
Planaria: Eye Sport

Question 8.
Choose the action of the sympathetic system from the following.
(a) Peristalsis becomes normal
(b) Heartbeat increases
(c) Gastric activities become normal
(d) Trachea contracts
Answer:
(b) Heartbeat increases

Question 9.
Based on the given model (A) complete (B).

Answer:
(i) Bacteria
(ii) Leptospira

Part – II

(A) Answer the following question. Carries 2 scores. (1 × 2 = 2)

Question 10.
Analyze the given statement and answer the following questions.
“Genetic engineering has made a great leap in the treatment of genetic diseases”.
(a) Name the treatment method indicated. (1)
(b) What is the specific peculiarity of this treatment method? (1)
Answer:
(a) Gene therapy
(b) It is a method of treatment in which genes that are responsible for diseases are removed and normal functional genes are inserted in their place.

(B) Answer any 1 of the questions from 11 and 12. Each carries 2 scores. (1 × 2 = 2)

Question 11.
Observe the illustration and answer the following questions.

(a) Fill (i). (1)
(b) What are the characteristics of organisms belonging to (ii)? (1)
Answer:
(a) (i) Cercopithecoidea.
(b) (ii) Developed brain, freely movable hands.

Question 12.
Analyze the given genetic makeup and answer the questions.

(a) Give the number of somatic chromosomes. (1)
(b) Is the individual with this genetic makeup male or female? Why?
Answer:
(a) 44
(b) Female, because XX are the sex chromosomes of females.

Part – III

(A) Answer any 3 questions from 13 to 16. Each carries 3 scores. (3 × 3 = 9)

Question 13.
Analyse the given table and arrange Columns B and C according to Column A.

A	B	C
Cornea	The part of the retina where. Plenty of photoreceptors are present.	Transmits impulses from photoreceptors to the visual centre in the brain.
Pupil	The projected transparent anterior part of the sclera.	Regulates the amount of light falling on the eyes.
Yellow Spot	The part of the retina from where the optic nerve begins.	Refracts light rays to focus on the retina.
	The aperture is seen at the center of the iris.	Point of maximum visual clarity.

Answer:

A	B	C
Cornea	The projected transparent anterior part of the sclera.	Refracts light rays to focus on the retina.
Pupil	The aperture is seen at the center of the iris.	Regulates the amount of light falling on the eyes.
Yellow Spot	The part of the retina where plenty of photoreceptors are present.	Point of maximum visual clarity.

Question 14.
Evaluate the statement and answer the questions.
“Ants moving in a line along a particular trail by the production of certain chemical substances”.
(a) Such chemicals are known as ____________ (1)
(b) Write two examples of these chemical substances. (1)
(c) Write the other two uses of these chemical substances. (1)
Answer:
(a) Pheromones
(b) Civetone, Muscone, Bombykol (any 2)
(c) Help in attracting mates.
To inform the availability of food
To determine the path of travel
Signalling dangers. (any 2)

Question 15.
Observe the illustration and answer the questions.

(a) Identify the part indicated (i). (1)
(b) Name any two chemicals which provide rigidity to the part indicated (i). (1)
(c) How do the germs that have crossed (i) are prevented from entering the cell? (1)
Answer:
(a) (i) Cell Wall
(b) Lignin, Cutine, Suberin (any 2)
(c) They are prevented from entering through the cell membrane by callose, a polysaccharide formed in the cell wall.

Question 16.
Analyze the information related to Tuberculosis and Malaria. (3)

• Classify them in the given table.
• Spread through the air
• Bacteria is the pathogen
• High fever with shivering and profuse sweating
• Spread through Anopheles mosquito
• Loss of body weight, fatigue, persistent cough
• Protozoa is the pathogen

Answer:

Tuberculosis	Malaria
Spread through the air.	Spread through Anopheles mosquito.
Bacteria is the pathogen.P	rotozoa is the pathogen.
Loss of body weight, fatigue, persistent cough.	High fever with shivering and profuse sweating.

(B) Answer the following question. Carries a 3 score. (1 × 3 = 3)

Question 17.
Analyze the picture given below and answer the questions.

(a) Identify (i). (1)
(b) Write any two functions of this part. (2)
Answer:
(a) (i) Myelin sheath/Schwann cells.
(b) Provides nutrients and oxygen to the axon.
Accelerate impulse.
Act as an electric insulator.
Protects the axon from external shocks. (any 2)

Part – IV

(A) Answer any 2 of the questions from 18 to 20. Each carries 4 scores. (2 × 4 = 8)

Question 18.
Change in the shape of Red blood cells in a genetic disease is given below. Analyze it an answer the questions.

(a) Name the disease indicated. (1)
(b) Why do the shape of Red Blood Cells change? (1)
(c) How does the deformity of red blood cells affect the body? (2)
Answer:
(a) Sickle Cell Anaemia
(b) Defects of genes cause deformities in the sequencing of amino acids which are the building blocks of hemoglobin.
(c) Decreases the oxygen-carrying capacity of red blood cells. The RBCs in the shape of sickles aggregate and block the flow of blood through the blood vessels.

Question 19.
Observe the illustration given below and answer the questions.

(a) Fill (i), (ii), (iii), (iv). (2)
(b) Which is the dominant character? (2)
(c) Why does the recessive trait in the first generation appear in the second generation? (1)
Answer:
(a) (i) r
(ii) Rr
(iii) Rr
(iv) rr
(b) Round
(c) During gametic formation the factors that determine a particular character segregate without getting mixed.

Question 20.
The following are the main concepts of the theory of evolution. Analyze it and answer the following questions.
(i) Accumulation of variations inherited through generations.
(ii) Origin of new species.
(iii) Struggle for existence.
(iv) Favourable variations are transferred to the next generation.
(v) Those with no favorable variations are destroyed and the survival of others.
(vi) Overproduction.
(a) Name of the evolutionary theory. (1)
(b) Rearrange the concepts given above in sequential order. (3)
Answer:
(a) Theory of Natural Selection/Darwinism.
(b) (vi) Overproduction.
(iii) Struggle for existence.
(v) Those with no favorable variations are destroyed and the survival of others.
(iv) Favorable variations are transferred to the next generation.
(i) Accumulation of variations inherited through generations.
(ii) Origin of new species.

(B) Answer any 1 question from 21 to 22. Each carries 4 scores. (1 × 4 = 4)

Question 21.
The feature of a fluid in the eye is given below. Analyze it and answer the following questions.

It is formed blood and is reabsorbed into blood

(a) Name the fluid. (1)
(b) What is its function? (1)
(c) Name the eye disease associated with this fluid. (1)
(d) How does this diseases can be rectified? (1)
Answer:
(a) Aqueous Humor
(b) Provides oxygen and nutrients to tissues of the eye
(c) Glaucoma
(d) By Laser Surgery

Question 22.
Analyze the illustration related to the process of blood clotting and answer the following questions.

(a) Name the enzyme indicated as “X”. (1)
(b) How does this enzyme form? (1)
(c) Write the subsequent steps involved in this process. (2)
Answer:
(a) X = Thromboplastin
(b) Tissues and platelets at the site of the wound degenerate to form thromboplastin.

(d) The red blood cells and platelets get entangled in the network of fibrin fibers to form the blood cot.

Part – V

(A) Answer any 1 question from 23 to 24. Each carries 5 scores. (1 × 5 = 5)

Question 23.
Redraw the diagram, and answer the following questions.

Redrawing diagram
(a) Identify and label the parts with their names. (1)
(i) Maintains equilibrium of the body. (1)
(ii) Controls voluntary movements. (1)
(iii) Acts as a relay station of impulses. (1)
(b) Name the part labeled “X” and write its function. (1)
Answer:
(a)

(b) X = Medulla Oblongata
Controls involuntary actions like heartbeat, breathing, etc.

Question 24.
Analyze the process related to the regulation of blood glucose levels and answer the questions.

(a) Identify the hormones indicated as X and Y. (1)
(b) Name the gland which produces these hormones. (1)
(c) Name the disease caused due to the reduced production of the hormone X. (1)
(d) Write the symptoms of this disease. (1)
(e) Write another action of the hormone Y in regulating the level of glucose in the blood. (1)
Answer:
(a) X = Insulin, Y = Glucagon
(b) Pancreas
(c) Diabetes Mellitus
(d) Increased appetite and thirst and frequent urination
(e) Synthesizes glucose from amino acids.

Students can read Kerala SSLC Biology Question Paper March 2023 with Answers English Medium and Kerala SSLC Biology Previous Year Question Papers with Answers helps you to score more marks in your examinations.

Kerala Syllabus Class 10 Biology Question Paper March 2023 with Answers English Medium

Time: 1½ Hours
Total Score: 40

Instructions:

• The first 15 minutes is cool-off time.
• You may use the time to read the questions and plan your answers.
• Answer only based on instructions and questions given.
• Consider score and time while answering.

Answer any 5 from Qn. No. 1 to 6. Each carries 1 score. (5 × 1 = 5)

Question 1.
Identify the word pair relation and fill in the blank. (1)
Planaria: Eye spot
Housefly: _____________
Answer:
Ommatidia

Question 2.
Choose the correct pair from the following options. (1)
ENT – Treatment of Eye
Cardiology – Treatment of Heart
Opthalmology – Treatment of Cancer
Answer:
Cardiology – Treatment of Heart

Question 3.
Correct mistakes if any in the underlined part of the given statements. (1)
(a) Gibberellin stimulates the breakdown of stored food to facilitate germination.
(b) Ethylene promotes the growth of terminal buds.
(c) Cytokinin maintains the dormancy of the embryo.
Answer:
(b) Auxin
(c) Abscisic Acid

Question 4.
The genetic makeup of human females is 44+XX and that of males is 44+XY. What do the XX and XY indicate? (1)
Answer:
Sex Chromosomes

Question 5.
Find out the odd one and write the common feature of others. (1)
Chimpanzee, Gorilla, Monkey, Oranguttan.
Answer:
Monkey. Others are included in hominoidea.

Question 6.
What does the illustration indicate? (1)

Answer:
Nucleotide

Answer any 6 questions from Q. No. 7 to 13. Each carries 2 scores. (6 × 2 = 12)

Question 7.
Write the name and functions of A and B in the given figure. (2)

Answer:
(a) Axon, which carries impulses from the cell body to the outside.
(b) Synaptic knob, which secretes neurotransmitters.

Question 8.
Analyze the given illustration and answer the questions.

(a) Which process does this illustration indicate? (1)
(b) How does this process cause variation? (1)
Answer:
(a) Crossing over
(b) Part of a DNA crosses over to become the part of another DNA. They cause differences in the distribution of genes. When these chromosomes are transferred to the next generation they cause variation in offspring.

Question 9.
Symptoms of a viral disease are given. Analyze them and answer the questions.

• Inflammation of the liver.
• White portions of the eyes and nails become yellow-colored.

(a) Identify the disease. (1)
(b) Why do the white portions of the eyes and nails become yellow-colored? (1)
Answer:
(a) Hepatitis
(b) Because of the presence of bilirubin in blood.

Question 10.
The details of the blood groups of two persons are given in the table. Analyze them and answer the questions.

Person	Antigen	Antibody	Rh Factor
X	B	a	Present
Y	A	b	Absent

(a) Identify the blood groups of persons X and Y. (1)
(b) Can Y receive blood from X? Why? (1)
Answer:
(a) X – B+ve
Y – A-ve
(b) No. The antigen in the donor’s blood reacts with the antibody in the recipient’s blood will react to each other to form a blood clot (Coagulation).

Question 11.
Choose suitable hints from the box and complete the table. (2)

Answer:

Disease	Vector	Pathogen
Malaria	Anopheles Mosquito	Plasmodium
Filariasis	Culex Mosquito	Filarial Worm

Question 12.
Analyze the given statements and answer the questions.
(i) Sudden withdrawal of the hand while touching on a hot object unknowingly.
(ii) Blinking of eyes when light suddenly falls on them.
(a) Name the reflex actions that take place in (i) and (ii). (1)
(b) What is reflex action? (1)
Answer:
(a) (i) Spinal reflex
(ii) Cerebral reflex.
(b) Reflex actions are the accidental and involuntary responses of the body, in response to stimuli.

Question 13.
The main concept of the Origin of life is given below. Analyze it and answer the questions.

Life originated in some other planet in the universe and accidentally reached the Earth.

(a) Which theory is mentioned here? (1)
(b) Which evidence supports this? (1)
Answer:
(a) Panspermia theory.
(b) The organic substances obtained from the meteors that fell on earth.

Answer any 5 from Qn. No. 14 to 20. Each carries 3 scores. (5 × 3 = 15)

Question 14.
Arrange columns B and C according to column A.

A. Parts	B. Peculiarity	C. Function
Cerebrum	Rod shaped part.	Maintenance of homeostasis.
Cerebellum	Situated just below the thalamus.	Controls involuntary actions like heartbeat, breathing, etc.
Medulla Oblongata	The second largest part of the brain.	Evokes sensations.
	The largest part of the brain.	Maintains equilibrium of the body.

Answer:

A. Parts	B. Peculiarity	C. Function
Cerebrum	The largest part of the brain	Evokes sensations
Cerebellum	The second largest part of the brain	Maintains equilibrium of the body
Medulla Oblongata	Rod-shaped part	Controls involuntary actions like heartbeat, breathing, etc.

Question 15.
Hints related to a disease are given. Analyze them and answer the questions.

• It is a genetic disease.
• Excess blood is lost even through minor wounds.

(a) Identify the disease. (1)
(b) Why excess blood is lost even through minor wounds in such patients? (1)
(c) How temporary relief is brought in, for such patients? (1)
Answer:
(a) Haemophilia.
(b) Protein that enables blood coagulation is absent and no clotting occurs.
(c) Temporary relief is obtained by identifying the deficient protein and injecting it.

Question 16.
A table showing the blood glucose levels of three persons before breakfast is given below. Analyze it and answer the questions.

Individual	Blood Glucose Level
A	82 mg/100 ml
B	178 mg/100 ml
C	104 mg/100 ml

(a) Which person is Diabetic?
(b) What is the cause of this disease?
(c) What are the symptoms of this disease?
Answer:
(a) Person B.
(b) Decreased production of insulin due to the destruction of beta cells. The inability of cells to utilize the insulin produced.
(c) Increased appetite and thirst, frequent urination.

Question 17.
Stages in the process of protein synthesis are given below. Arrange them in sequential order.

• Protein is synthesized.
• mRNA reaches the ribosome.
• mRNA reaches outside the nucleus.
• Amino acids are added based on the information in mRNA.
• tRNA brings different kinds of amino acids to ribosomes.
• mRNA forms from DNA.

Answer:

• mRNA forms from DNA.
• mRNA reaches outside the nucleus.
• mRNA reaches ribosomes.
• tRNA brings different kinds of amino acids to ribosomes.
• Amino acids are added based on the information in mRNA.
• Protein is synthesized.

Question 18.
The flow chart and hints related to a theory of evolution are given below. Analyze them and answer the questions.

(a) Choose suitable hints from the box and fill in A and B. (1)
(b) Which theory is indicated in the flow chart? (1)
(c) What is the limitation of this theory? (1)
Answer:
(a) A – Struggle for existence.
B – Natural selection.
(b) Theory of Natural selection/Darwinism.
(c) Darwin could not explain the reason for variation.

Question 19.
Give a reason for the following.
(a) There is no vision in the Blindspot.
(b) Persons with color blindness are not selected for jobs like that of drivers, pilots, etc.
(c) The deficiency of Vitamin A results in Night blindness.
Answer:
(a) Photoreceptors are absent in blind spots.
(b) They cannot distinguish green and red colors.
(c) Retinal, the visual pigment, is formed from vitamin A.

Question 20.
Observe the illustration showing the production of insulin through Genetic engineering and answer the questions.

(a) Name enzymes X, Y. (1)
(b) What is the role of plasmid In this process? (1)
(c) Does the succeeding generations of bacteria produced in this way have the ability to produce insulin? Why? (1)
Answer:
(a) X – Restriction endonuclease (genetic scissor), Y – Ligase (genetic glue).
(b) Plasmid is used as a vector for carrying the insulin gene.
(c) Yes, because they carry the gene responsible for insulin production.

Answer any 2 from Qn. no. 21 to 23. Each carries 4 scores. (2 × 4 = 8)

Question 21.
Observe the illustration and answer the questions.

(a) What is the process indicated in this illustration? (1)
(b) Name the white blood cells involved in this process. (1)
(c) Write the steps involved in this process in sequential order. (2)
Answer:
(a) Phagocytosis
(b) Monocytes, Neutrophils.
(c) The phagocyte engulfs the pathogens in a membrane sac.
The membrane sac combines with a lysosome.
The enzyme in the lysosome degenerates and destroys the pathogens.

Question 22.
Redraw the diagram. Name and label the parts indicated below. (For drawing 1 score) (2)

(a) The transparent anterior part of the sclera. (1)
(b) The point of maximum visual clarity. (1)
(c) Transmits impulses to the visual center of the brain. (1)
Answer:

Question 23.
Analyze the illustration of hormonal disorders and answer the questions.

(a) Name the hormone indicated as X. (1)
(b) Identify the disorders A and B. (1)
(c) What are the symptoms of A and B? (2)
Answer:
(a) Somatotropin (Growth Hormone)
(b) A – Gigantism.
B – Acromegaly.
(c) A – Excessive growth of the body.
B – Growth of the bones on the face, jaws, and fingers.

Students can read Kerala SSLC Biology Question Paper March 2024 with Answers English Medium and Kerala SSLC Biology Previous Year Question Papers with Answers helps you to score more marks in your examinations.

Kerala Syllabus Class 10 Biology Question Paper March 2024 with Answers English Medium

Time: 1½ Hours
Total Score: 40

Instructions:

• The first 15 minutes is cool-off time.
• You may use the time to read the questions and plan your answers.
• Answer only based on instructions and questions given.
• Consider score and time while answering.

Answer any 5 from questions 1-6. One score each. (5 × 1 = 1)

Question 1.
Identify the pigment present in the given photoreceptor cell. (1)

Answer:
Rhodopsin or Iodopsin

Question 2.
Which among the following is not a component of a nucleotide? (1)
(a) Phosphate
(b) Sugar
(c) Protein
(d) Nitrogen base
Answer:
(c) Protein

Question 3.
Find out the correct one from the given pairs. (1)
Monocyte: Stimulates other white blood cells.
Lymphocyte: Engulls and destroys germs.
Neutrophil: Identifies and destroys germs specifically.
Eosinophil: Synthesises chemicals required for the inflammatory responses.
Answer:
Eosinophil: Synthesizes chemicals required for inflammatory responses

Question 4.
Identify the word pair relation and fill in the blanks. (1)
Fruit formation: Auxin
Ripening of fruits: ___________
Answer:
Ethylene

Question 5.
The technology used to identify the location of a gene in the DNA responsible for a particular trait is: (1)
(a) Gene therapy
(b) Gene mapping
(c) DNA profiling
(d) DNA fingerprinting
Answer:
(b) Gene mapping

Question 6.
Correct the mistakes in the underlined part of the given statements. (1)
(a) The Panspermia argues that life originated on another planet and accidentally reached the Earth.
(b) Huso de Vries is the scientist who put forward the scientific theory on evolution called the Natural Selection theory.
(c) Organs that are similar in structure and perform different functions are called homologous organs.
Answer:
(b) Charles Darwin

Answer any 6 from the questions 7-13. 2 scores each. (6 × 2 = 12)

Question 7.
Analyze the symptoms of a disease given and answer the questions.

(a) Identify the disease. (1)
(b) Write the cause of the disease. (1)
Answer:
(a) Alzheimer’s.
(b) Accumulation of an insoluble protein in the neural tissues of the brain. Neurons get destroyed.

Question 8.
Analyze the given table related to the activities of hormones and complete it properly. (2)

A (Causes)	B (Gland)	C (Disease)
(i)	(ii)	Cretinism
Reabsorption of water in the kidney decreases	(iii)	(iv)

Answer:
(i) Hypothyroidism refers to a decrease in the amount of thyroxine during the foetal stage or infancy.
(ii) Thyroid
(iii) Hypothalamus
(iv) Diabetes insipidus

Question 9.
Analyze the illustration and answer the questions.

(a) Identify the process. (1)
(b) What is the importance of this process? (1)
Answer:
(a) Crossing over of Chromosomes.
(b) Responsible for creating genetic variation within individuals of a species.

Question 10.
Write appropriate reasons for the given statements.
(a) An ash-colored thick coating is formed in the throat of Diphtheria diphtheria-affected person. (1)
(b) Complete cure is not possible for Haemophilia. (1)
Answer:
(a) The toxins produced by the bacteria (Corynebacterium diphtheriae) destroy the mucus membrane of the throat.
(b) It is a genetic disease.

Question 11.
Choose the activities of the Sympathetic system from the box. (2)

Production of saliva decreases, Urinary bladder contracts, Gastric activities become Normal, Production of saliva increases, Glycogen is converted to glucose

Answer:

• Production of saliva decreases.
• Glycogen is converted to glucose.

Question 12.
Analyze the given illustration and answer the questions.

(a) Which theory of evolution is proved by this experiment? (1)
(b) What are the main postulates put forward by this theory? (1)
Answer:
(a) Theory of Chemical Evolution/Oparinhaldane hypothesis.
(b) Life originated by the change that occurred in the chemical substances in water, under specific conditions of the primitive earth.

Question 13.
How does smoking harmfully affect the following organ systems? (2)
Respiratory system
Circulatory system
Answer:
(a) Lung cancer, Bronchitis, Emphysema. (Any two)
(b) Hypertension, arteries lose elasticity, and decrease in functional efficiency.

Answer any 5 from questions 14 – 20. 3 scores each. (5 × 3 = 15)

Question 14.
Observe the illustration of impulse transmission through synapse and answer the following questions.

(a) Which part is denoted as ‘X’ ?
(b) Which chemical is secreted from ‘X’?
(c) Why does impulse travel only from X to Y?
Answer:
(a) X: synaptic knob
(b) Neurotransmitter (Acetylcholine/dopamine/GABA)
(c) Synaptic knob (X) secret neurotransmitters which is receives an impulse from adjacent neurons by Dendrite (Y).

Question 15.
Analyze the given stages in the process of detecting smell and write in sequential order. (3)

• Experiences smell.
• Aromatic particles enter the nostrils.
• Generate impulses.
• Stimulate the Olfactory receptors.
• These aromatic particles dissolve in the mucus.
• Impulses reach the brain.

Answer:

• Aromatic particles enter the nostrils.
• Aromatic particles dissolve in the mucus.
• Stimulates the olfactory receptors.
• Generate impulses.

Question 16.
Analyse the given table and arrange columns B and C according to column A.

A. Disease	B. Symptoms	C. Transmission
Tuberculosis	Dark yellow colour to the mucus membrane, white portion of the eyes, and the nails.	Spread by culex mosquitos.
Hepatitis	High fever with shivering and profuse sweating, headache, vomiting, diarrhea, and anemia.	When the patient speaks, coughs, or sneezes, the pathogens spread into the air.
Malaria	Loss of body weight, fatigue, and persistent cough.	Contaminated food and water, blood components, and excreta of the patient.
	The appearance of red dish scaly rashes that cause itching.	Spread by female anopheles mosquito.

Answer:

A. Disease	B. Symptoms	C. Transmission
Tuberculosis	Loss of body weight, Fatigue, and persistent cough.	When the patient speaks, coughs or sneezes, the pathogens spread into the air.
Hepatitis	Dark yellow colour to the mucus membrane, white portion of the eyes, and the nails.	Contaminated food and water, blood components and excreta of the patient.
Malaria	High fever with shivering and profuse sweating, headache, vomiting, Diarrhea, and anemia.	Spread through female anopheles mosquitoes.

Question 17.
Analyze the given statement and answer the questions. (3)
“The basis of blood grouping is the presence of antigen A and antigen B in red blood cells.”
According to this, how many blood groups are there in humans?
Write the antigen and antibody of each group.
Answer:

Blood Group	Antigen	Antibodies
A	A	B
B	B	A
AB	A and B	Nil
O	Nil	A and B

Question 18.
Some of the features of nucleic acids and their constituents are given below. Arrange them on the table suitably.

Ribose sugar, Uracil, Deoxyribose sugar, Double helical model, Single strand, Thymine

Answer:

DNA	RNA
Deoxyribose sugar	Ribose sugar
Double helical model	Single stand
Thymine	Uracil

Question 19.
Observe the illustration of bacteria and answer the questions.

(a) Which part is denoted as ‘X’? (1)
(b) What is the significance of ‘X’ in the process of genetic engineering? (2)
Answer:
(a) X: Plasmid/Circular DNA of bacteria
(b) Plasmid acts as vectors to transfer genes from one cell to another.
Vectors that contain recombined genes enter target cells and the new genes become a part of the genetic constitution of target cells.

Question 20.
Write any three pieces of evidence from biochemistry and physiology to prove bacteria and humans evolved from a common ancestor. (3)
Answer:

• Enzymes control chemical reactions.
• Energy is stored in ATP molecules.
• Genes determine the hereditary traits.
• Carbohydrates, proteins, and fats are the basic substances.

Answer any 2 questions from 21 – 23. Each carries 4 scores. (2 × 4 = 8)

Question 21.
The function of regulating the level of calcium in the blood is illustrated. Analyze it and answer the following questions.

(a) Which gland produces the hormone indicated as ‘X’? (1)
(b) Which hormone is indicated by ‘Y’? (1)
(c) Write down the other functions of these hormones. (2)
Answer:
(a) Thyroid Gland
(b) Parathormone
(c) Calcitonin – Lowering the calcium levels in your blood.
Parathormone – increasing the calcium level when they are too low.

Question 22.
Explain how the following strategies of defense help in immune function.
(a) Phagocytosis
(b) Fever
(c) Healing of Wounds
(d) Blood Clotting
Answer:
(a) Engulfing and destroying germs.
(b) An increase in body temperature reduces the multiplication of pathogens and increases the effect of phagocytosis.
(c) Reduces the chance of infection by the healing wounds reduction.
(d) Helps to prevent bleeding and checks the entry of pathogens through wounds.

Question 23.
Redraw the diagram, and identify and label the parts with their names.

Redraw the diagram.
(a) The part that carries impulses out of the cell body. (1)
(b) The part that receives messages from the adjacent neuron. (1)
(c) The part that carries impulses to the cell body. (1)
Answer:

Students can read Kerala SSLC Chemistry Board Model Paper March 2022 with Answers English Medium and Kerala SSLC Chemistry Previous Year Question Papers with Answers helps you to score more marks in your examinations.

Kerala Syllabus Class 10 Chemistry Board Model Paper March 2022 with Answers English Medium

Time: 1½ Hours
Total Score: 40

Instructions:

• There is a ‘Cool-off time’ of 15 minutes in addition to the writing time.
• Use this time to get familiar with questions and to plan your answer.
• Questions with different scores are given as distinct parts.
• Read the instructions carefully before answering the questions.
• Keep in mind, the score and time while answering the questions.
• The maximum score for questions from 1 to 24 will be 40.

Part – I
Questions from 1 to 9 carry 1 score each

A. Answer any 4 questions from 1 to 6. (4 × 1 = 4)

Question 1.
Which Subshell is common to all shells?
Answer:
s-subshell

Question 2.
The number of molecules present in 1 GMM N₂ is _____________
Answer:
6.022 × 10²³ or Avagadro number or N_A

Question 3.
Which one of the following metals reacts with hot water?
[Au, Cu, Ag, Mg]
Answer:
Mg

Question 4.
Fill up suitably:
OH: Hydroxyl Group
-COOH: _____________
Answer:
-COOH: Carboxylic Group

Question 5.
Complete the given chemical equation.
NH₄Cl → _____________ + HCl
Answer:
NH₄Cl → NH₃ + HCl

Question 6.
Which is the method used to concentrate Sulphide ores?
Answer:
Froth Floatation

B. Answer all questions from 7 to 9. (3 × 1 = 3)

Question 7.
In f-block elements, the last electron is filled in _____________ subshell.
Answer:
Inner Penultimate ‘f’ subshell

Question 8.
Which substance is deposited at the Cathode, when molten Sodium Chloride is electrolysed?
[Oxygen, Chlorine, Sodium, Hydrogen]
Answer:
Sodium

Question 9.
In electrolytes, _____________ are responsible for the conduction of electricity.
Answer:
Charged Ions

Part – II
Questions from 10 to 12 carry 2 scores each

A. Answer the following question. (1 × 2 = 2)

Question 10.
(a) Which of the following chemicals are used to prepare ammonia (NH₃) in the laboratory? (1)
[NaCl, Ca(OH)₂, CaCl₂, NH₄Cl]
(b) Ammonia gas produced is passed through quick lime. Give reason. (1)
Answer:
(a) Ca(OH)₂, NH₄Cl
(b) To remove moisture.
Quick lime is a good drying agent.

B. Answer any one question from 11 to 12. (1 × 2 = 2)

Question 11.
The volume of 1 mole of any gas at STP is 22.4 L. What will be the volume of 34 g NH₃ at STP? (2)
[1 GMM NH₃ = 17 g]
Answer:
No. of moles in STP = \(\frac{\text { Given mass }}{\text { GMM }}=\frac{34}{17}\) = 2 moles
Volume of 2 moles = 2 × 22.4 = 44.8 L

Question 12.
Copper is electroplated on an iron ring.
(a) Which electrolyte is used here? (1)
(b) Which metal is connected to the positive terminal of the battery? (1)
Answer:
(a) Copper Sulphate (CuSO₄) Solution
(b) Pure Copper

Part – III
Questions from 13 to 17 carry 3 scores each

A. Answer any three questions from 13 to 16. (3 × 3 = 9)

Question 13.
Match columns A, B, and C suitably: (3)

A. Alloy Steel	B. Property	C. Use
Stainless Steel	High Resistance	For the manufacture of permanent magnets
Nichrome	Magnetic Nature	For the manufacture of utensils
Alnico	Hard	For making heating coils

Answer:

A. Alloy Steel	B. Property	C. Use
Stainless Steel	Hard	For the manufacture of utensils
Nichrome	High Resistance	For making heating coils
Alnico	Magnetic Nature	For the manufacture of permanent magnets

Question 14.
In element A (symbol is not real), the last two electrons are added to the 4s subshell.
(a) Write down the subshell electronic configuration of A. (1)
(b) Which period does it belong to? (1)
(c) Find its group number. (1)
Answer:
(a) 1s², 2s², 2p⁶, 3s², 3p⁶, 4s²
(b) 4th Period
(c) 2nd Group

Question 15.
N₂ (g) + 3H₂ (g) \(\rightleftharpoons\) 2NH₃ (g) + Heat
How do the following changes affect the rate of forward reaction in the given system at equilibrium?
(a) Pressure is decreased. (1)
(b) Temperature is increased. (1)
(c) More H₂ is added. (1)
Answer:
(a) The rate of forward reaction will be decreased. Because due to forward reaction number of molecules decreases.
(b) The rate of forward reaction decreases. Because the forward reaction is exothermic.
(c) Rate of forward reaction increases. Because the concentration of reactant increases.

Question 16.
Choose the name of the reaction from the given box and complete the table.

Substitution Reaction, Thermal Cracking, Addition Reaction, Combustion, Polymerisation

Chemical Equation	Name of Reaction
CH2 = CH2 + H2 → CH3 – CH3	_________________________
CH4 + 2O2 → CO2 + 2H2O	_________________________
CH3 – CH3 + Cl2 → CH3 – CH2 – Cl + HCl	_________________________

Answer:

Chemical Equation	Name of Reaction
CH2 = CH2 + H2 → CH3 – CH3	Addition Reaction
CH4 + 2O2 → CO2 + 2H2O	Combustion
CH3 – CH3 + Cl2 → CH3 – CH2 – Cl + HCl	Substitution Reaction

B. Answer the following question. (1 × 3 = 3)

Question 17.
Examine the following compounds and answer the questions.
(i) CH₃ – O – CH₃
(ii) CH₃ – CH₂ – CH₂ – OH

(iv) CH₃ – CH₂ – OH
(a) Find out the isomeric pairs. (2)
(b) Which is the functional group of CH₃ – O – CH₃? (1)
Answer:

(b) -O- (Alkoxy Group)

Part – IV
Questions from 18 to 22 carry 4 scores each

A. Answer any two questions from 18 to 20. (2 × 4 = 8)

Question 18.
The relation between pressure and volume of a fixed mass of gas at constant temperature is given in the table.

Pressure (P) Atm	Volume (V) L	P × V
1	200	200
2	(a)	200
(b)	50	(c)

(a) Find the values of a, b and c. (3)
(b) Which gas law is applied here? (1)
Answer:
(a) a = 100 L
b = 4 atm
c = 200
(b) Boyle’s Law

Question 19.
The structural formula of a hydrocarbon is given:

(a) Write the molecular formula of the given hydrocarbon. (1)
(b) How many carbon atoms are there in the longest carbon chain? (1)
(c) Name the branch present. (1)
(d) Write its IUPAC name. (1)
Answer:
(a) C₇H₁₆
(b) 6
(c) Methyl
(d) 3-Methyl Hexane

Question 20.
The following chemical equations represent the reactions taking place in the blast furnace during the manufacture of iron.

• C + O₂ → CO₂ + Heat
• CO₂ + C + Heat → 2CO
• Fe₂O₃ + 3CO → 2Fe + 3CO₂
• CaCO₃ → CaO + CO₂
• CaO + SiO₂ → CaSiO₃

(a) Which is the ore of iron used in the blast furnace? (1)
(b) Which substance acts as the reducing agent in this process? (1)
(c) What is the role of CaO in this process? (1)
(d) Which one of the given chemical equations represents slag formation? (1)
Answer:
(a) Fe₂O₃ or Haematite
(b) CO or Carbon Monoxide
(c) Used as Flux to remove the impurity in the iron ore.
(d) CaO + SiO₂ → CaSiO₃

B. Answer any one question from 21 to 22. (1 × 4 = 4)

Question 21.
Choose the correct answer from the box.

Ethanoic Acid, Sodium Hydroxide, Methanol, Glycerol, 95.6% Ethanol

(a) Which alcohol is known as wood spirit? (1)
(b) Which substance is known as rectified spirit? (1)
(c) Name the acid present in vinegar. (1)
(d) Which is the by-product in the manufacture of soap? (1)
Answer:
(a) Methanol
(b) 95.6% Ethanol
(c) Ethanoic Acid
(d) Glycerol

Question 22.
A few drops of concentrated sulphuric acid are added to sugar.
(a) What do you observe? (1)
(b) Which property of concentrated sulphuric acid is shown here? (1)
(c) Why concentrated sulphuric acid is not used as a drying agent in the preparation of ammonia? (1)
(d) Which substance is used to identify sulphate salts? (1)
(NaCl, KCl, BaCl₂, BaSO₄)
Answer:
(a) Sugar gets charred to carbon. CO₂ gas and water vapour are liberated.
(b) Dehydrating Property.
(c) Concentrated sulphuric acid reacts with basic ammonia and forms ammonium sulphate salt.
(d) BaCl₂

Part – V
Questions from 23 to 24 carry 5 scores each

A. Answer any one question from 23 to 24. (1 × 5 = 5)

Question 23.
The atomic number of an element X is 13. (Symbol is not real)
(a) Write down the subshell electronic configuration of element X. (1)
(b) Write down its subshell electronic configuration using the symbol of the preceding noble gas. (1)
(c) Which block does it belong to? (1)
(d) Find the total number of electrons in all the p subshells of this element. (1)
(e) Write down the subshell electronic configuration of the X3+ ion. (1)
Answer:
(a) X₁₃ = 1s², 2s², 2p⁶, 3s², 3p¹
(b) [Ne] = 3s² 3p¹
(c) P-Block
(d) 7
(e) X³⁺ = 1s², 2s², 2p⁶

Question 24.
The diagram of a galvanic cell is given.

[Hint: Order of Reactivity Mg > Zn > Fe > Cu > Ag]
(a) What is the energy change taking place in a galvanic cell? (1)
(b) At which electrode does oxidation take place? (1)
(c) Which metal does act as the cathode? (1)
(d) If Silver and Copper are used as electrodes to construct the cell, which metal acts as the anode? (1)
(e) Write down the chemical equation of the reaction taking place at the Copper electrode in this case. (1)
Answer:
(a) Chemical Energy → Electrical Energy
(b) Anode (Zn rod)
(c) Cu
(d) Copper
(e) Cu → Cu²⁺ + 2e^– (Oxidation)

Students can read Kerala SSLC Chemistry Board Model Paper March 2023 with Answers English Medium and Kerala SSLC Chemistry Previous Year Question Papers with Answers helps you to score more marks in your examinations.

Kerala Syllabus Class 10 Chemistry Board Model Paper March 2023 with Answers English Medium

Time: 1½ Hours
Total Score: 40

Instructions:

• The first 15 minutes is cool-off time.
• You may use the time to read the questions and plan your answers.
• Answer only based on instructions and questions given.
• Consider score and time while answering

Section – A

Answer any four questions from 1 to 5. Each question carries 1 score.

Question 1.
The most stable outermost subshell electronic configuration of ₂₄Cr is: (1)
(3d¹⁰ 4s¹, 3d⁴ 4s², 3d⁵ 4s¹, 3d⁹ 4s¹)
Answer:
3d⁵ 4s¹

Question 2.
The volume of 1 GMM of any gas at STP is __________ (1)
Answer:
22.4 L or 22400 ml

Question 3.
Which is the product obtained at the cathode when sodium chloride solution is electrolyzed? (1)
(H₂, Cl₂, Na, O₂)
Answer:
H₂

Question 4.
Write the name of the catalyst used in the industrial production of sulphuric acid. (1)
Answer:
Vanadium Pentoxide (V₂O₅)

Question 5.
Which one of the following organic compounds undergoes an addition reaction? (1)
(CH₃ – CH₃, CH₄, CH₃Cl, CH₂ = CH₂)
Answer:
CH₂ = CH₂

Section – B

Answer any four questions from 6 to 10. Each question carries 2 scores.

Question 6.
A few drops of cone. H₂SO₄ is added to blue-colored copper sulphate crystals taken in a watch glass.
(a) Write the observation. (1)
(b) Which property of sulphuric acid is exhibited here? (1)
Answer:
(a) Blue colour of copper sulphate disappears.
(b) Dehydrating property.

Question 7.
(a) Which of the following metals is purified using the distillation method? (1)
(Tin, Lead, Zinc, Iron)
(b) Which property of the metal is used here? (1)
Answer:
(a) Zinc
(b) Low Boiling Point

Question 8.
Analyze the following chemical equation.

(a) Name of the unsaturated compound obtained as the product is __________ (1)
(b) Which type of reaction is this? (1)
(Substitution, Addition, Thermal Cracking, Polymerisation)
Answer:
(a) Propene
(b) Thermal Cracking

Question 9.
The number of molecules in a given sample of ammonia (NH₃) is 2 × 6.022 × 10²³. (1)
(a) Find the number of moles present in it.
(Atomic Mass: N = 14, H = 1)
(b) What is the mass of this sample? (1)
Answer:
(a) 2 moles
(b) 2 × 17 = 34 g (molecular mass NH₃ = 17)

Question 10.
The structure of an aromatic hydrocarbon is given.

(a) What is the name of this compound? (1)
(b) Write the molecular formula of this compound. (1)
Answer:
(a) Benzene
(b) C₆H₆

Section – C

Answer any four questions from 16 to 20. Each question carries 3 cores.

Question 11.
A gas kept in cylinder A having volume 5 L at 4 atm pressure is completely transferred to cylinder B to volume 10 L at constant temperature.
(a) What is the volume of the gas in cylinder B? (1)
(b) What will be the pressure in cylinder B? (1)
(c) Which Gas law is associated with this situation? (1)
Answer:
(a) 10 L
(b) 2 atm
V₁ = 5 L V₂ = 10 L, P₁ = 4 atm, P₂ = ?
⇒ P₁V₁ = P₂V₂
⇒ 4 × 5 = P₂ × 10
⇒ P₂ = \(\frac{4 \times 5}{10}\) = 2
(c) Boyle’s Law: At a constant temperature the volume of a definite mass of gas is inversely proportional to its pressure.
If ‘P’ is the pressure and ‘V’ the volume then
V ∝ \(\frac{1}{P}\), P × V is a constant.

Question 12.
Certain facts regarding an organic compound are given.

• It contains four carbon atoms.
• There are only single bonds between the carbon atoms.
• It is an alicyclic compound.

(a) Draw the structure of this compound. (1)
(b) Write the molecular formula of this compound. (1)
(c) Write the structure of an alkene with the same molecular formula. (1)
Answer:

(b) C₄H₈
(c) CH₃ – CH = CH – CH₃ But-2-ene or CH₂ – CH – CH₂ – CH₃ But-1-ene

Question 13.
The atomic number of an element X is 26. (Symbol is not real)
(a) Write the subshell electronic configuration of X. (1)
(b) Find the group number of X. (1)
(c) Write any one property of the elements belonging to the block in which X is included. (1)
Answer:
(a) ₂₆X = 1s², 2s² 2p⁶, 3s² 3p⁶ 3d⁶, 4s²
(b) 8
(c) All are metals.
Exhibits various oxidation states.
Produce colored compounds.
Electrons are filled in the penultimate ‘d’ subshell.
Shows similarity in groups and periods.

Question 14.
Observe the figure in which a copper plate is immersed in an AgNO₃ (Silver Nitrate) solution. (Reactivity: Cu > Ag)

(a) The reaction taking place here is a redox reaction. Why? (1)
(b) What change can be observed on the copper plate? (1)
(c) Write the equation of the oxidation reaction taking place here. (1)
Answer:
(a) Oxidation and Reduction take place simultaneously.
Cu → Cu²⁺ + 2e^– (Oxidation)
Ag¹⁺ + 1e^– → Ag (Reduction)
(b) Copperplate will be coated with silver.
(c) Cu → Cu²⁺+ 2e^–
Cu + 2Ag⁺ → Cu²⁺ + 2Ag (Redox Reaction)

Question 15.
CH₃ – COOH is the condensed formula of an organic compound.
(a) To which category does the compound belong? (1)
(alcohol, ether, ester, acid)
(b) Write the IUPAC name of this compound. (1)
(c) Write any one use of this compound. (1)
Answer:
(a) Acid
(b) Ethanoic Acid
(c) 5 – 8% of ethanoic acid is used as vinegar.
In the manufacture of rayon.
In the rubber and silk industry.

Section – D

Answer any 4 questions from 16 to 20. Each question carries 4 scores.

Question 16.
A reversible reaction at equilibrium is given.
2NO (g) + O₂ (g) \(\rightleftharpoons\) 2NO₂ (g) + Heat
(a) Write the equation of the forward reaction. (1)
(b) How do the following changes affect the rate of forward reaction?
(i) Adding more oxygen (1)
(ii) Increasing pressure (1)
(c) What is the effect of a catalyst in a reversible reaction at equilibrium? (1)
Answer:
(a) 2NO (g) + O₂ (g) → 2NO₂ + Heat
(b) (i) Rate of forward reaction increases. More product is formed.
(ii) Rate of forward reaction increases. Because due to forward reaction number of molecules decreases.
(c) Catalyst speeds up both forward and backward reactions. So equilibrium is attained earlier.

Question 17.
A and B are two organic compounds with different functional groups and having same molecular formula C₃H₈O.
(a) Write the structural formula of compound A having -OH as a functional group. (1)
(b) Write the structural formula of B. (1)
(c) Write the IUPAC name of B. (1)
(d) Write the structure of the position isomer of A. (1)
Answer:
(a) CH₃ – CH₂ – CH₂ – OH (Propan-1-ol)
(b) CH₃ – O – CH₂ – CH₃
(c) Methoxyethane

Question 18.
Aluminium is a widely used metal in daily life.
(a) Which is the ore of aluminium? (1)
(b) Which method is used for the concentration of this ore? (1)
(c) Which is the reducing agent used for the production of aluminium? (1)
(d) Why cryolite is used during the production of aluminium? (1)
Answer:
(a) Bauxite (Al₂O₃.2H₂O)
(b) Leaching (Dissolves in NaOH Alkali)
(c) Electricity
(d) Cryolite reduces the melting point of alumina.
Cryolite increases the electrical conductivity.

Question 19.
The atoms of elements A and B contain 3 shells each (symbols are not real). A belongs to group 2 and B belongs to group 16.
(a) Write the subshell electronic configuration of A. (1)
(b) What is the valecny of element B? (1)
(c) Write the chemical formula of the compound formed by the reaction of A and B? (2)
Answer:
(a) ₁₂A = 1s², 2s² 2p⁶, 3s²
(b) ₁₆B = 1s², 2s² 2p⁶, 3s² 3p⁴
Valency = 2
(c) Valency of A = 2
Valency of B = 2
Chemical Formula = AB

Question 20.
A galvanic cell is constructed using Mg and Cu as electrodes. (Reactivity: Mg > Cu)
(a) What is the energy change taking place in a galvanic cell? (1)
(b) Which is the anode of the given galvanic cell? (1)
(c) Write the equation of the chemical reaction taking place at the cathode. (1)
(d) How many galvanic cells can be constructed using the metals Mg, Zn and Cu? (1)
Answer:
(a) Chemical energy is converted to electrical energy.
(b) Mg (Magnesium)
(c) Cu²⁺ + 2e^– → Cu
(d) Three (Mg – Zn, Mg – Cu, Zn – Cu)

Students can read Kerala SSLC Chemistry Board Model Paper March 2024 with Answers English Medium and Kerala SSLC Chemistry Previous Year Question Papers with Answers helps you to score more marks in your examinations.

Kerala Syllabus Class 10 Chemistry Board Model Paper March 2024 with Answers English Medium

Time: 1½ Hours
Total Score: 40

Instructions:

• The first 15 minutes is cool-off time.
• You may use the time to read the questions and plan your answers.
• Answer only based on instructions and questions given.
• Consider score and time while answering.

Section – A

Answer any four questions from 1 to 5. Each question carries 1 score.

Question 1.
Which of the following subshells is not possible? (1)
(3f, 3d, 3p, 4f)
Answer:
3f

Question 2.
Which product is obtained at the cathode when molten sodium chloride is electrolyzed? (1)
Answer:
Sodium

Question 3.
The highly concentrated aqueous solution of ammonia is known as __________ (1)
Answer:
Liquor Ammonia

Question 4.
Write the general name of the compounds having a carboxylic (-COOH) functional group. (1)
Answer:
Carboxylic Acids (RCOOH)

Question 5.
State Boyle’s Law. (1)
Answer:
At a constant temperature, the volume of a definite mass of gas is inversely proportional to its pressure.
If P is the pressure and V is the volume, then P × V is a constant.

Section – B

Answer any four questions from 6 to 10. Each question carries 2 scores.

Question 6.
Select the correct statements regarding gases from the following. (2)
(a) The real volume of gas molecules is much less when compared to the total volume of the gas.
(b) The gas molecules move in one direction only.
(c) The gas molecules are in random motion in all directions.
(d) The collisions of gas molecules are inelastic.
Answer:
(a) The real volume of gas molecules is much less when compared to the total volume of the gas.
(c) The gas molecules are in random motion in all directions.

Question 7.
A glass rod dipped in concentrated hydrochloric acid (conc. HCl) when shown over ammonia gas, thick white fumes are formed.
(a) Which is the compound formed in this experiment? (1)
(b) Write the chemical equation of the formation of this compound. (1)
Answer:
(a) Ammonium Chloride (NH₄Cl)
(b) NH₃ + HCl → NH₄Cl

Question 8.
Write the IUPAC names of the following compounds.
(a) CH₃ – CH₂Cl (1)
(b) CH₃ – CH₂ – O – CH₃ (1)
Answer:
(a) Chloro Ethane
(b) Methoxy Ethane

Question 9.
Analyse the following equation which shows the fermentation of molasses.

(a) Identify the ‘Enzyme A’. (1)
(b) Which is the product obtained when was is subjected to fractional distillation? (1)
Answer:
(a) Zymase
(b) Rectified Spirit

Question 10.
(a) Which method is used to purify zinc metal? (1)
(b) Which property of zinc is utilized here? (1)
Answer:
(a) Distillation
(b) Low boiling Point

Section – C

Answer any four questions from 11 to 15. Each question carries 3 scores.

Question 11.
The given table shows the results of an experiment on a fixed mass of gas at constant pressure.

(a) Identify the gas law represented by this table. (1)
(b) Write any one situation in daily life to which this can be related. (1)
(c) Find the volume of this gas at 100 K. (1)
Answer:
(a) Charles Law
(b) If an inflated balloon is kept in sunlight, it will burst.
(When temperature increases, the volume of the air inside the balloon increases.)
(c) According to Charles’s law, at constant pressure, \(\frac{V}{T}\) is a constant.
\(\frac{V}{T}\) = 0.03
When T = 100 K
\(\frac{V}{100K}\) = 0.03
V = 0.03 × 100 = 3 L
The volume of the gas at 100 K is 3 L.

Question 12.
A copper plate is dipped in AgNO₃ solution and kept for some time.
(a) Write any two observations concerning this reaction that takes place here. (2)
(b) Write the reason for the change that occurred in the solution. (1)
Answer:
(a) Silver is deposited on the copper plate, and the silver nitrate solution turns blue.
(b) Displacement Reaction.

Question 13.
Subshell electronic configurations of two elements are given. [Symbols are not real]
X – [Ne] 3s² 3p¹
Y – [Ne] 3s² 3p⁵
(a) Find the groups of X and Y. (1)
(b) What is the valency of Y? (1)
(c) Write the chemical formula of the compound formed by the combination of X and Y. (1)
Answer:
(a) X = 13, Y = 17
(b) 1
(c) XY₃

Question 14.
(a) Starting from ethene (CH₂ = CH₂) how will you prepare the following compounds? Write the chemical equation of each reaction.
(i) CH₃ – CH₃ (1)
(ii) CH₃ – CH₂Cl (1)
(b) Which reaction is used to get polythene from ethene? (1)
Answer:
(a) (i) CH₂ = CH₂ + H₂ → CH₃ – CH₃
(ii) CH₂ = CH₂ + HCl → CH₃ – CH₂Cl
(b) Polymerisation

Question 15.
The structural formula of an organic compound is given.
CH₃ – CH₂ – CH = CH₂
(a) This compound belongs to ___________ family. (1)
(alkane, alkene, alkyne)
(b) Write the molecular formula and IUPAC name of this compound. (1)
(c) Write the structural formula of the alicyclic compound with the same molecular formula of the above-given compound. (1)
Answer:
(a) Alkene
(b) IUPAC Name – But-1-ene
Molecular formula – C₄H₈

Section – D

Answer any 4 questions from 16 to 20. Each question carries 4 scores.

Question 16.
Analyze the given equation for the main step in the manufacture of Sulphuric acid.
2SO₂ + O₂ \(\rightleftharpoons\) 2SO₃ + Heat
(a) Write the name of the process used for the manufacture of sulphuric acid. (1)
(b) Which is the catalyst used in the manufacture of Sulphuric acid? (1)
(c) What is the effect of the following changes in the amount of SO₃ produced?
(i) More oxygen is added. (1)
(ii) Pressure is increased. (1)
Answer:
(a) Contact Process
(b) Vanadium Pentoxide (V₂O₅)
(c) (i) Forward reaction increases, and more product is formed.
(Concentration of reactant is increased, more amount is formed, rate of forward reaction increases)
(ii) Forward reaction increases, and more product is formed.
(When pressure increases, the reaction in which there is a decrease in no. of moles is favored)

Question 17.
The compound ‘A’ added to the blast furnace decomposes to give a product ‘B’ which acts as the flux in the production of Iron.
(a) Identify the compounds A and B. (2)
(b) Write the equation of slag formation in a blast furnace. (1)
(c) Which is the compound acting as the reducing agent in the blast furnace? (1)
Answer:
(a) A = Calcium Carbonate (CaCO₃)
B = Calcium Oxide (CaO)
(b) CaO + SiO₂ → CaSiO₃
(c) Carbon Monoxide

Question 18.
In a metal ‘M’ reaction with chlorine at different conditions, two compounds MCl₂ and MCl₃ are formed.
(a) Find the oxidation states of M in each of these compounds. (1)
(b) If the 3d subshell of this metal contains 6 electrons, write the complete subshell electronic configuration of this metal atom. (1)
(c) Write the subshell electronic configuration of the metal ion in MCl₂. (1)
(d) Write any one property of the elements in the block to which this metal belongs. (1)
Answer:
(a) MCl₂ – +2, MCl₃ – +3
(b) 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s²
(c) 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶
(The oxidation state of that metal is +2, and 2 electrons are donated)
(d) Coloured Compounds/Different Oxidation State

Question 19.
An organic compound with -OH as the functional group has the molecular formula C₃H₈O.
(a) Write two possible structural formulae of this compound. (2)
(b) Write the structure and IUPAC name of a functional isomer of the above compounds. (2)
Answer:
(a)

and CH₃ – CH₂ – CH₂ – OH
(b) CH₃ – CH₂ – O – CH₃
IUPAC Name – Methoxy Ethane

Question 20.
Observe the following figures.

(a) In which of these beakers does a chemical reaction take place? (1)
(b) Write the chemical equation of the reaction. (1)
(c) How will you construct a galvanic cell using the materials provided in the beakers? Draw the figure of the galvanic cell and explain.
Answer:
(a) Beaker A
(b) Zn + CuSO₄ → ZnSO₄ + Cu
(c)

A galvanic cell or voltaic cell is an arrangement in which chemical energy is converted into electrical energy using a redox reaction. Arrange the apparatus as shown in the picture. Take two beakers, one containing 100 mL ZnSO₄ solution and the second containing the same amount of CuSO₄ solution with the same concentration. Dip Zn rod in ZnSO₄ solution and Cu rod in CuSO₄ solution. Connect the negative terminal of the voltmeter to the Zn rod and the positive terminal to the Cu rod. Connect the two solutions in the beakers using a salt bridge (A long filter paper that is moistened with KCl solution can be used instead of a salt bridge).

Students can read Kerala SSLC Chemistry Question Paper March 2021 with Answers English Medium and Kerala SSLC Chemistry Previous Year Question Papers with Answers helps you to score more marks in your examinations.

Kerala Syllabus Class 10 Chemistry Question Paper March 2021 with Answers English Medium

Time: 1½ Hours
Total Score: 40

Instructions:

• 20 minutes is given as cool-off time.
• Use cool-off time to read the questions and plan your answers.
• Attempt the questions according to the instructions.
• Keep in mind, the score and time while answering the questions.
• The maximum score for questions from 1 to 32 will be 40.

Each question from 1 to 8 carries 1 score.

Question 1.
What is the maximum number of electrons that can be accommodated in the ‘f’ subshell? (1)
(2, 6, 10, 14)
Answer:
14

Question 2.
Identify the alkene among the given hydrocarbons. (1)
(C₂H₆, C₂H₄, C₂H₂, CH₄)
Answer:
C₂H₄

Question 3.
Metals like gold and platinum are found in their native state in the earth’s crust. Why? (1)
Answer:
Platinum and gold are less reactive metals.

Question 4.
One gram atomic mass (1 GAM) of any element contains _____________ atoms. (1)
Answer:
6.022 × 10²³

Question 5.
Select the monomer of natural rubber. (1)
[Vinyl Chloride, Ethene, Isoprene, Tetrafluoro Ethene]
Answer:
Isoprene

Question 6.
Which drying agent is used to remove moisture present in ammonia gas? (1)
Answer:
Quick Lime Calcium Oxide (CaO)

Question 7.
Which is the electrolyte used for electroplating silver on an iron bangle? (1)
Answer:
A mixture of sodium cyanide and silver cyanide or silver nitrate solution.

Question 8.
What is the energy change that takes place in a galvanic cell? (1)
Answer:
Chemical energy changes to electrical energy.

Each question from 9 to 16 carries 2 scores.

Question 9.
(a) When molten Sodium Chloride is electrolyzed, which is the gas liberated at the anode? (1)
(b) Write the chemical equation of the reaction taking place at the cathode. (1)
Answer:
(a) Chlorine
(b) Na⁺ + 1e^– → Na

Question 10.
(a) From the given subshell electronic configuration, write the correct electronic configuration of Chromium (₂₄Cr). (1)
(i) 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁴ 4s²
(ii) 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹
(b) What is the reason for this selection? (1)
Answer:
(a) (ii) 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹
(b) Half-filled and filled ‘d’ subshells are more stable.

Question 11.
Given below are two chemical equations. (2)
(a) CH₂ = CH₂ + H₂ → A
(b) A + Cl₂ + Sunlight → B + HCl
Identify the compounds A and B.
Answer:

Question 12.
The flow chart of the industrial preparation of sulphuric acid is given. Complete it. (2)

Answer:

Question 13.
Some metals are given in the box.

(a) Which metal among these reacts vigorously with dilute HCl? (1)
(b) Which gas is liberated by this reaction? (1)
Answer:
(a) Mg
(b) Hydrogen (H₂)

Question 14.
The structure of an alkyne is given.

(a) What is the molecular formula of this compound? (1)
(b) Write the IUPAC name. (1)
Answer:
(a) C₄H₆
(b) But-1-yne

Question 15.
Two methods are used to convert concentrated ore into its oxide.
(a) Calcination
(b) Roasting
What is the difference between these?
Answer:
(a) Calcination – The ore is heated below its melting point in the absence of air.
(b) Roasting – The ore is heated below its melting point in the presence of air.

Question 16.
CH₄, C₂H₆, C₃H₈, and C₄H₁₀ are the members of a homologous series.
(a) What is the molecular formula of the 6th member of this series? (1)
(b) Write the general formula of this homologous series. (1)
Answer:
(a) C₆H₁₄
(b) C_nH_2n+2

Each question from 17 to 24 carries 3 scores.

Question 17.
The chemical formulae of two different chlorides of iron (Fe) are given below.
(i) Ferrous Chloride – FeCl₂
(ii) Ferric Chloride – FeCl₃
[Hint: Oxidation State of Chlorine Atom (Cl) = -1; Atomic Number of iron (Fe) = 26]
(a) In which compounds iron (Fe) show a +2 oxidation state? (1)
(b) Write the Subshell electronic configuration of Fe³⁺. (1)
(c) Why does iron show different oxidation states? (1)
Answer:
(a) FeCl₂
(b) Fe³⁺, 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵
(c) The difference in energy level between the outermost ‘s’ subshell and the penultimate (last but one) ‘d’ subshell is much less. So in chemical reactions not only the outermost ‘s’ subshell but also the penultimate ‘d’ subshell electrons are lost.

Question 18.
Some chemical reactions taking place in blast furnaces are given.
(i) Fe₂O₃ + 3CO → 2Fe + 3CO₂
(ii) CaCO₃ → CaO + CO₂
(iii) CaO + SiO₂ → CaSiO₃
(a) What is the chemical formula of haematite? (1)
(b) Which compound reduces haematite? (1)
(c) Identify the flux used here. (1)
Answer:
(a) Fe₂O₃
(b) CO
(c) CaO

Question 19.
The structural formula of a hydrocarbon is given.

(a) How many carbon atoms are there in the main chain? (1)
(b) What is the position number of the branch? (1)
(c) Write the IUPAC name of this compound. (1)
Answer:
(a) 5
(b) 3
(c) 3-methyl pentane

Question 20.
Some metals and their refining methods are given. Find the appropriate pair. (3)

Answer:

• Tin – Liquation
• Copper – Electrolytic Refining
• Zinc – Distillation

Question 21.
Outermost Subshell electronic configuration of two elements X and Y are given.
X = 3s²
Y = 3s²3p⁵
(Symbols are not real)
(a) What is the valency of the element X? (1)
(b) Which element shows metallic character? (1)
(c) Write the chemical formula of the compound formed by the combination of X and Y. (1)
Answer:
(a) 2
(b) X
(c) XY₂

Question 22.
The graph for the reversible reaction.
N₂ (g) + 3H₂ (g) \(\rightleftharpoons\) 2NH₃ (g) + Heat is given below.

(a) Identify and write the chemical equation associated with ‘Reaction C’ and ‘Reaction D’. (2)
(b) What is the peculiarity of the point A? (1)
Answer:
(a) Reaction C – Forward reaction
N₂ (g) + 3H₂ (g) → 2NH₃ (g) + Heat
Reaction D – Backward reaction
2NH₃ (g) + Heat → N₂ (g) + 3H₂ (g)
(b) The point ‘A’ represents the state of equilibrium. From this point the speed of forward and backward reactions are equal. But the reactions never stops.

Question 23.
The CO₂ gas kept at STP has a volume of 112 L.
[Hint: Molecular Mass – 44]
(a) Find the number of moles of CO₂. (1)
(b) Calculate the mass of 112 L CO₂. (1)
(c) How many molecules of CO₂ are present in it? (1)
Answer:
(a) 5 mol (\(\frac{112}{22.4}\) = 5)
(b) 44 × 5 = 220 g
(c) 5 × 6.022 × 10²³

Question 24.
Analyze the figure and answer the following questions.

(a) In which test tube the iron nail undergoes a colour change? (1)
(b) Write the name of the reaction taking place here. (1)
(c) Write the chemical equation of this reaction. (1)
Answer:
(a) C (Fe in CuSO₄ Solution)
(b) Displacement Reaction
(c) CuSO₄ + Fe → FeSO₄ + Cu
Cu²⁺ + Fe → Fe²⁺ + Cu

Each question from 25 to 32 carries 4 scores.

Question 25.
The subshell electronic configuration of an element is given.
1s² 2s² 2p⁶ 3s²
(a) Write the atomic number of this element. (1)
(b) To which block this element belongs? (1)
(c) Identify the period number and group number of this element. (2)
Answer:
(a) 12
(b) ‘s’ block
(c) Period – 3; Group – 2

Question 26.
The structural formulae of two organic compounds are given.
(i) CH₃ – O – CH₂ – CH₃
(ii) CH₃ – CH₂ – CH₂ – OH
(a) Write the IUPAC name of the first compound. (1)
(b) These two organic compounds are isomers. Why? (1)
(c) Which type of isomerism is exhibited by them? (1)
(d) Write the structural formula of the position isomer of the second compound. (1)
Answer:
(a) Methoxy Ethane
(b) Same molecular formula but different structural formula. Differs both in physical and chemical properties.
(c) Functional group isomerism

Question 27.
The figure of a galvanic cell is given.
[Hint: Zinc is more reactive than Copper]

(a) Identify anode and cathode. (2)
(b) What will be the direction of the flow of electrons? (1)
(c) Write the chemical equation of the reaction taking place at the anode. (1)
Answer:
(a) Anode – Zn
Cathode – Cu
(b) From Zn to Cu (From anode to cathode)
(c) Zn → Zn²⁺ + 2e^–

Question 28.
The chemical equation of the industrial preparation of ammonia is given below.
N₂ (g) + 3H₂ (g) \(\rightleftharpoons\) 2NH₃ (g) + Heat
How do the following factors influence the rate of forward reaction?
(a) Ammonia is removed from the system. (1)
(b) Temperature is increased. (1)
(c) Pressure is increased. (1)
(d) More nitrogen is added. (1)
Answer:
(a) Speed of forward reaction increases.
(b) Speed of forward reaction decreases.
(c) Speed of forward reaction increases.
(d) Speed of forward reaction increases.

Question 29.
Identify the suitable concentration method from the box and then complete the table.

Answer:
(a) Levigation (Hydraulic Washing)
(b) Magnetic Separation
(c) Froth Flotation
(d) Leaching

Question 30.
(a) What happens to the size of an air bubble rising from the bottom of an aquarium? What is the reason? (2)
(b) Which gas law is associated with this phenomenon? (1)
(c) State this law. (1)
Answer:
(a) Size increases
As the balloon rises pressure decreases and volume increases.
(b) Boyles law
(c) When the temperature remains constant the volume of a fixed mass of gas is inversely proportional to its pressure.
v ∝ \(\frac{1}{p}\) when ‘t’ is constant.

Question 31.
From the given statements, write the statements applicable to gases. (4)
(i) The energy of molecules is very high.
(ii) Attractive force between molecules is very high.
(iii) The distance between molecules is very large.
(iv) Freedom of movement of molecules is much less.
(v) As the collision of molecules is perfectly elastic, there is no loss of energy.
(vi) When compared to total volume, the real volume of molecules is much less.
Answer:
(i) The energy of molecules is very high.
(ii) The distance between the molecules is very high
(v) As the collision between the molecules is perfectly elastic there is no loss in energy.
(vi) When compared to the total volume the real volume of molecules is very less.

Question 32.
Find out the appropriate reactions and match the columns A, B and C suitably. (4)

Answer: