Kerala SSLC Chemistry Question Paper March 2021 with Answers English Medium

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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: