Kerala SSLC Chemistry Board Model Paper March 2023 with Answers English Medium

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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)