Kerala SSLC Chemistry Question Paper 2025 and Answer Key, Download PDF

Kerala SSLC Question Paper 2025 and Answer Key: The Kerala SSLC (Secondary School Leaving Certificate) Exam 2025 is a crucial milestone for Class 10 students in Kerala. Among the various subjects, Chemistry is considered one of the most important due to its conceptual depth and scoring potential. The exam is being conducted from 9:30 AM to 11:15 AM, with an additional 15 minutes allotted for reading the question paper. In this article, we will provide the Kerala SSLC Question Paper 2025 PDF along with the answer key by experts, helping students analyze their performance and estimate their scores.

Check: Kerala SSLC Class 10 Chemistry Exam Analysis 2025

Kerala SSLC Question Paper 2025: Paper Pattern Overview

The Kerala SSLC Question Paper 2025 comprised a total of 20 questions carrying 40 marks in total. The exam duration was 1.5 hours, with an additional 15 minutes allotted for reading the question paper.

The question paper was structured into four sections as follows:

• Section A – 1-mark questions
• Section B – 2-mark questions
• Section C – 3-mark questions
• Section D – 4-mark questions

Kerala SSLC Chemistry Question Paper 2025 

Students can check the Kerala SSLC Chemistry Question Paper 2025 here.

Kerala SSLC Chemistry Answer Key 2025

Now that the paper is over, students might be waiting for the answer key. The answer key helps the students to estimate their total score. Students can check the link to the answer key here. 

SECTION - A 

(Answer any 4 questions from 1 to 5)

1. Which of the given compounds is a mineral of Aluminium?
(Calamine, Cuprite, Cryolite, Magnetite)
Answer: Cryolite

2. Which polymer is formed from isoprene?
Answer: Natural Rubber

3. Find the total number of atoms in 2 GMM water (H₂O).
Answer:

• 1 GMM (gram molecular mass) of water (H₂O) = 18g

• 1 molecule of H₂O contains 3 atoms (2 hydrogen + 1 oxygen)

• 1 mole of H₂O contains (6.022 × 10²³) molecules

• Total atoms in 1 mole = 3 × (6.022 × 10²³) = 1.806 × 10²⁴ atoms

• For 2 GMM = 2 × (1.806 × 10²⁴) = 3.612 × 10²⁴ atoms

4. Which is the product obtained when SO₃ gas is dissolved in concentrated sulphuric acid?
Answer: Oleum (H₂S₂O₇)

5. Many of the metals in _______ block are used as catalysts in the petroleum industry.
(s, p, d, f)
Answer: d-block

SECTION - B 

(Answer any 4 questions from 6 to 10)

6. Classify the following compounds into alkanes, alkenes, and alkynes:
C₂H₄, C₅H₁₂, C₃H₈, C₇H₁₂

Answer:

• Alkanes: C₅H₁₂ (Pentane), C₃H₈ (Propane)

• Alkenes: C₂H₄ (Ethene), C₇H₁₂ (Heptene)

• Alkynes: (None in the given list)

7. Two gases Oxygen and Nitrogen at STP are given:

(a) Calculate the number of molecules in 64 g of Oxygen.

• Molecular mass of O₂ = 32 g

• 1 mole of O₂ = 6.022 × 10²³ molecules

• Moles in 64 g O₂ = 64/32 = 2 moles

• Total molecules = 2 × 6.022 × 10²³ = 1.204 × 10²⁴ molecules

(b) Calculate the mass of Nitrogen having the same volume as that of 64 g of Oxygen.

• At STP, equal volumes of gases contain equal moles.

• 64 g of O₂ = 2 moles

• For N₂, 2 moles = 2 × 28 g = 56 g
  Answer: Mass of Nitrogen = 56 g

8. Two reactions related to the extraction of metals are given. Among these reactions, identify calcination and roasting.

(a) Cu₂S ore is converted to Cu₂O by heating.
Answer: Roasting (since Cu₂S reacts with oxygen)

(b) Carbonates and hydroxides of metals decompose to form their oxides.
Answer: Calcination (since it involves thermal decomposition without oxygen)

9. Identify A and B.

(a) CH₃ - OH + CO → (A) (in presence of catalyst, high temperature & pressure)
Answer: A = CH₃COOH (Acetic Acid)

(b) CHCl₃ + Cl₂ → (B) + HCl
Answer: B = CCl₄ (Carbon Tetrachloride)

10. The chemical formula of a compound is C₂H₆O.

(a) Write the structural formula of any one of the functional isomers.
Answer:

• Ethanol: CH₃CH₂OH

• Dimethyl ether: CH₃OCH₃

(b) Write the IUPAC name of this functional isomer.
Answer:

• Ethanol: Ethanol

• Dimethyl ether: Methoxy methane

11. Copper is electroplated on an iron bangle.

(a) Which electrolyte is used here?
Answer: Copper sulfate (CuSO₄) solution

(b) Write any one of the advantages of electroplating.
Answer: It prevents corrosion and enhances appearance.

(c) Does the intensity of color of electrolyte change during this process? Why?
Answer: Yes, because Cu²⁺ ions are deposited on iron, decreasing their concentration in the solution.

12. Subshell electronic configuration of an element ‘A’ is given in two different ways.

(i) 1s² 2s² 2p⁶ 3s² 3p⁶ 3d²
(ii) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

(a) Which of these is the correct subshell electronic configuration? Why?
Answer: (ii) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² is correct because the 4s subshell is filled before 3d according to the Aufbau principle.

(b) Identify the block in the periodic table to which this element belongs.
Answer: s-block (since the last electron enters the 4s orbital).

13. Two reversible reactions are given:

(I) H₂(g) + I₂(g) ⇌ 2HI(g) + Heat
(II) 2SO₂(g) + O₂(g) ⇌ 2SO₃(g) + Heat

(a) Identify the reaction in which pressure has no effect.
Answer: Reaction (I), because the number of gas molecules on both sides is the same.

(b) How do the following factors influence the amount of product in reaction (II)?

(i) Increase in temperature
Answer: Decreases the formation of SO₃, as the reaction is exothermic (Le Chatelier’s Principle).

(ii) Increase in pressure
Answer: Increases the formation of SO₃, as there are fewer gas molecules on the product side.

14. Chemical equations of some reactions are given.

(i) CH₃ - CH = CH - CH₃ + HBr → CH₃ - CH₂ - CHBr - CH₃
(ii) n CH₂ = CH - Cl → [ CH₂ - CH ]n (Cl attached)

(a) Which types of reactions are these?
Answer:

• (i) Addition reaction (Hydrohalogenation of alkene)

• (ii) Polymerization reaction (Formation of polyvinyl chloride, PVC)

(b) Identify the product in reaction (ii) and write any one use of it.
Answer:

• Product: Polyvinyl Chloride (PVC)

• Use: PVC is used in making pipes, cables, and plastic materials.

SECTION - D (4 Marks Each)

(Answer any 4 questions from 16 to 20)

16. Manganese (Mn) is an element that belongs to the d-block in the periodic table.

(a) Outer subshell electronic configuration of Mn is 3d⁵4s².
Answer: 3d⁵4s²

(b) Find the atomic number of Manganese.
Answer: Atomic number = 25

(c) Find the oxidation state of Mn in Mn₂O₇.
Answer: Let oxidation state of Mn = x
Mn₂O₇ → 2x + 7(-2) = 0
2x - 14 = 0
x = +7

(d) Write period number and group number of Manganese.
Answer:

• Period number: 4

• Group number: 7

(e) Write the subshell electronic configuration of Mn⁴⁺ ion.
(Hint: Oxidation state of Oxygen = -2)
Answer:

• Mn: [Ar] 3d⁵4s²

• Mn⁴⁺: [Ar] 3d³ (since 2 electrons are lost from 4s and 2 from 3d)

17. A few drops of solution ‘X’ is added to Magnesium sulfate solution taken in a test tube. A white precipitate is formed.

(a) What is ‘X’?
Answer: Sodium carbonate (Na₂CO₃) or Ammonium carbonate ((NH₄)₂CO₃)

(b) What is the chemical name of the white precipitate formed here?
Answer: Magnesium carbonate (MgCO₃)

(c) What happens to the white precipitate when dilute hydrochloric acid is added?
Answer: The precipitate dissolves, forming a clear solution due to the reaction:
MgCO₃ + 2HCl → MgCl₂ + CO₂ + H₂O

(d) Which type of salt is identified by this experiment?
Answer: Carbonate salt (CO₃²⁻ containing salt)

18. Three metals Ag, Mg, Cu and their salt solutions are given.

(a) How many galvanic cells can be constructed using these metals?
Answer: Three (Possible pairs: Mg-Cu, Mg-Ag, Cu-Ag)

(b) If we construct a galvanic cell using the most reactive metal and the least reactive metal from the given metals, identify the cathode and anode.
Answer:

• Most reactive metal: Mg

• Least reactive metal: Ag

• Anode: Mg (because it is more reactive and undergoes oxidation)

• Cathode: Ag (because it is less reactive and undergoes reduction)

(c) Write the chemical equation of the reaction which takes place at the anode and cathode in the above cell.
Answer:

• Anode reaction (oxidation):
  Mg → Mg²⁺ + 2e⁻

• Cathode reaction (reduction):
  2Ag⁺ + 2e⁻ → 2Ag

19. Iron is a very important metal in the industrial and construction field.

(a) Write the name and chemical formula of ore of iron used in the industrial production of iron.
Answer: Hematite (Fe₂O₃)

(b) Write the chemical equation of slag formation in the industrial production of iron.
Answer:

• CaO + SiO₂ → CaSiO₃

• (Calcium oxide reacts with silicon dioxide to form slag, calcium silicate)

(c) Which mineral of iron is known as ‘fool’s gold’?
Answer: Pyrite (FeS₂)

(d) Write the names of two alloy steels which contain the same constituent elements.
Answer: Stainless steel and tool steel (Both contain iron, carbon, and chromium)

20. Match the following suitably.

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