Q1. [1] § 1.2.2 Decomposition Reaction § 1.2.3 Displacement Reaction
When ferrous sulphate crystals are heated in a test tube, we observe that :
- (A) A colourless gas with no smell is evolved.
- (B) A brown gas is evolved.
- (C) The green colour of the salt fades and a gas with the smell of burning sulphur is evolved.
- (D) The green colour of the salt fades and no gas is evolved.
Previously asked in CBSE board exam
2026 31/2/1 Q19
Generated by claude-sonnet-4-6 · 2026-06-14 10:31 · grounding rag
Model Answer
(C) The green colour of the salt fades and a gas with the smell of burning sulphur is evolved.
Explanation
When FeSO₄ is heated, it decomposes into Fe₂O₃, SO₂, and SO₃. The green colour fades (Fe²⁺ → Fe³⁺ forming red-brown Fe₂O₃) and SO₂/SO₃ gases produce the characteristic smell of burning sulphur. This is directly described in Activity 1.5 of Chapter 1.
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