Kerala Syllabus Class 9 Chemistry Model Question Paper Set 4 English Medium

Teachers recommend solving Kerala Syllabus 9th Standard Chemistry Question Papers Set 4 to improve time management during exams.

Kerala Syllabus Std 9 Chemistry Model Question Paper Set 4 English Medium

Score :40
Time: 1 1⁄2 hrs.

Instructions

• First 15 minutes is given as cool off time. This time is to be spent for reading and understanding the questions.
• Answer the questions according to the directions.
• Score and time to be considered while answering.

I. Answer any four questions from 1-5. Each carries 1 score. (4 × 1 = 4)

Question 1.
Who discovered neutrons?
(J.J Thomson, Earnest Rutherford, James Chadwick, Neils Bohr)
Answer:
James Chadwick

Question 2.
Identify the relationship in the first pair and fill in the blanks in the second pair.
Electronegativity scale : Linus Pauling
Electron dot diagram : ________
Answer:
Newton Lewis

Question 3.
Name the gas produced when sodium reacts with water. (Oxygen, Hydrogen, Chlorine, Carbon dioxide)
Answer:
Hydrogen

Question 4.
Which one of the following is a fundamental particle? (Proton, Electron, Neutron, Alpha particle)
Answer:
Electron

Question 5.
What is the total number of groups in the modern periodic table? (18, 32, 6, 7)
Answer:
18

II. Answer any four questions from 6-10. Each carries 2 scores. (4 × 2 = 8)

Question 6.
Find out the wrong statements from those given below and correct them.
a) Transition elements show the properties of both metals and non-metals.
b) The size of atoms increases down the group in the periodic table.
c) The mass of atoms mainly depends upon the masses of neutrons and electrons.
d) The size of atoms decreases across a period in the periodic table.
Answer:
a) Metalloids show the properties of both metals and non-metals.
c) The mass of atoms mainly depends on the masses of neutrons and protons.

Question 7.
Find out the oxidation number of phosphorus in the compounds given below)
Hint. Oxidation number O = -2, H = +1
a) P₂O₅
b) H₃PO₄
Answer:
a) P₂O₅
2P + -2 × 5=0
2P + -10 = 0
2P = ⁺10
P = ⁺10/2 = ⁺5)

b) H₃PO₄
(⁺1 × 3) +P + (^–2 × 4) = 0
⁺3 + P + ^–8 = 0
P + 5 = 0
P = ⁺5

Question 8.
The electron configuration of certain elements is given in the table. (Symbols are not real).
A – 2,8,1
B – 2,8,8
C – 2,8,8,1
a) Which of these belong to the same period?
b) Which of these belong to the same group?
c) Which of these elements is more stable why?
Answer:
a) Same period : A and B
b) Same group: A and C
c) B is more stable. Because it has stable octet electron configuration in the outermost shell.

Question 9.
Illustrate the formation of sodium fluoride using an electron-dot diagram.
Hint: atomic number Na = 11 F = 9
Answer:

Question 10.
Match these given in Columns A and B Suitably

A	B
Gains electrons	Noble gas
Loses electrons	Covalent bonding
Shares electrons	Oxidation
Neither gains nor loses electrons	Reduction

Answer:
Answer:
Gains electrons – Redution
Loses electrons – Oxidation
Shares electrons – Covalent bonding
Neither gains nor loses electrons – Noble gases

III. Answer any four questions from 11 to 15. Each carries 3 scores. (4 × 3 = 12)

Question 11.
The symbol of an atom is \({ }_{35}^{17} \mathrm{Cl}\)
a) Find out the number of protons and neutrons in this atom.
b) Write the electron configuration of this atom.
c) Illustrate the shell model of this atom.
Answer:
a) Number of protons = 17
Number of neutrons =18
b) 2, 8, 7

Question 12.
Carbon combines with chlorine to form a compound carbon tetrachloride.
[Hint: Atomic Number: C = 6, C1 = 17]
a) How many electrons are required to complete the octet of a carbon atom?
b) How many atoms of chlorine should combine with a carbon atom to complete the octet?
c) Which type of covalent bond is present in carbon tetrachloride?
(Single bond, Double bond, Triple bond)
Answer:
a) Four
b) Four
c) Single bond

Question 13.
a) Which are the isotopes of hydrogen?
b) Illustrate the shell electron configuration of these isotopes.
c) Write the use of any one of these isotopes.
Answer:
a) Protium (\({ }_1^1 \mathrm{H}\)), Deuterium (\({ }_1^2 \mathrm{H}\)), Tritium (\({ }_1^3 \mathrm{H}\))

c) Deuterium (\({ }_1^2 \mathrm{H}\)) isotope is used to make heavy water in nuclear reactors.

Question 14.
Which of the statements given below are related to Rutherford?
a) Put forward the idea of definite orbits.
b) Proposed the planetary model of atom.
c) Conducted gold-foil experiment.
d) Discovered electrons.
e) Discovered the nucleus of an atom.
f) Put forward the plum pudding model of atom.
Answer:
b) Proposed the planetary model of atom.
c) Conducted gold-foil experiment.
e) Discovered the nucleus of an atom.

Question 15.
Classify the following statements as applicable to transition elements and main group elements.
a) Shows periodicity in electron filling.
b) All are metals.
c) Shows similarities in periods and groups.
d) Includes elements of all category.
e) Includes elements of all states of matter.
f) Shows variable valency.
Answer:
Transition elements
b) All are metals.
c) Shows similarities in periods and groups.
f) Shows variable valency.
Main group elements
a) Shows periodicity in electron filling.
d) Includes elements of all category.
e) Includes elements of all states of matter.

IV. Answer any four questions from 16-20. Each carries 4 scores. (4 × 4 = 16)

Question 16.
Certain anions in acids are given below.
i) \(\mathrm{CO}_3^{2-}\)
ii) \(\mathrm{SO}_4^{2-}\)
iii) \(\mathrm{NO}_3^{-}\)
(iv) \(\mathrm{PO}_4^{3-}\)
a) Write the chemical formula of acids containing these anions.
b) Write the chemical equation of the neutralisation reaction between sodium hydroxide and nitric acid.
c) Write the chemical formula of the acid and base required to form potassium chloride.
Answer:
a) H₂CO₃, H₂SO₄, HNO₃, H₃PO₄
b) NaOH+ HNO₃ → NaNO₃ + H₂O
c) HCl and KOH
(HCl + KOH → KCI +H₂O)

Question 17.
Water is a polar molecule.
a) What is a polar molecule?
b) What is the reason for the polar nature of molecules?
c) What are the characteristics of water as a polar molecule?
Answer:
a) Covalent molecules having partial charges on component atoms are called polar molecules.
b) Great difference in electronegativity values of component atoms causes polar nature. The more electronegative atom attracts the shared electron pair towards it, and attains a partial negative charge. (Other atom attains a partial positive charge)
c)

• Even though the molecular mass of water is less, it is in the liquid state. This is due to the polar nature.
• Due to polar nature, water can dissolve both organic and inorganic substances.
• Water is a universal solvent. This is also due to its polar nature.

Question 18.
Add a few drops of phenolphthalein in water taken in a trough. Cut a small piece of sodium and place it carefully into the trough.
a) What will be the observation?
b) What is the nature of the compound formed?
c) Write the balanced equation of the chemical reaction.
Answer:
a) Vigorous reaction takes place.
The solution turns to pink.
A gas is liberated.
b) Basic nature.
c) 2Na+2H₂O → 2NaOH + H₂

Question 19.
A Chemical reaction is given below.

a) What happens to the oxidation number of each atom in this reaction?
b) At the elemental state, the oxidation number is zero. Why?
c) What type of reaction is this? Give reason.
d) Find out the oxidising and reducing agents in this reaction.
Answer:
a) Oxidation number of carbon increases from zero to +4.
Oxidation number of oxygen decreases from zero to -2.

b) At elemental state electrons are equally shared by atoms. Electrons are neither lost nor gained. So oxidation number is assumed to be zero.

c) Redox reaction:
Because oxidation and reduction take place simultaneously.

d) Oxidising agent – oxygen
Reducing agent – carbon

Question 20.
Match columns A, B and C related with the modern periodic table suitably.

A	B	C
Transition elements	17th group	Rare earths
Halogens	3-12 groups	Artificial elements
Lanthanoids	7th period	Coloured compounds
Actinoids	6th period	Non-metallic nature

Answer:

A	B	C
Transition elements	3-12 groups	Coloured compounds
Halogens	17th group	Non-metallic nature
Lanthanoids	6th period	Rare earths
Actinoids	7th period	Artificial elements