General Instructions for Paper

What is the interpretation of the reaction H2S(g) + Cl2(g) → 2HCl(g) + S(s)?

An aqueous solution turns red litmus solution blue. Excess addition of which of the following solutions would reverse the change?

Which of the following compounds is covalent in nature?

What are the correct coefficients for the reaction C3H8 + xO2 → yCO2 + 2H2O?

‘Alum’ is an example of what type of substance?

Which element can react with oxygen to give a compound with a high melting point that is also water soluble?

Which of the following is not correctly matched with the gaseous product on decomposition?

What are the four properties of an ionic compound?

In the experiment with KHCO3 as the reactant, which statement is not correct?

Hydrogen sulfide (H2S) is a strong reducing agent. Which of the following reactions shows its reducing action?

Total Duration: 90 minutes
Maximum Marks: 40
Three sections in the question paper:
- Section A: 24 questions, attempt any 20
- Section B: 24 questions, attempt any 20
- Section C: 12 questions, attempt any 10
Equal marks for all questions, no negative marking.

Reaction: H2S(g) + Cl2(g) → 2HCl(g) + S(s)
- Interpretation: H2S gets oxidized, Cl2 gets reduced.
Aqueous solution changes red litmus to blue; reversing the change can be achieved by adding:
- Hydrochloric acid.
Identifying covalent compounds:
- Carbon tetrachloride is covalent in nature.
Reaction coefficients in combustion: C3H8 + xO2 → yCO2 + 2H2O
- Correct coefficients: p=1, q=5, r=3, s=4.
Alum classification:
- Alum is a double salt.
An element reacting with oxygen to form a water-soluble compound with a high melting point:
- Calcium is a likely candidate.
Decomposition products:
- Incorrect match: H2CO3 decomposes into H2 (not a typical gaseous product).
Properties of ionic compounds:
- Ionic compounds form crystals, are very brittle, have high melting points, and conduct electricity when melted.
Kinetic reaction changes with KHCO3:
- Statement that is not correct: Lime water will turn milky.
Reducing agent properties of hydrogen sulfide (H2S):
- Reducing action illustrated by the reaction: CuSO4 + H2S → CuS + H2SO4.