Question

Assertion : When ferrous sulphate crystals are heated strongly, its colour
changes from green to brown.
Reason: It undergoes displacement reaction.​

Answer 1

The assertion is true but the reason is false.

• When we strongly heat the ferrous sulphate, chemical reaction takes place and ferric oxide is being produced.
• The ferrous sulphate has light green colour whereas the ferric oxide has brown colour. So, the statement of the given assertion is absolutely true.
• Now, in the final stage of chemical reaction during the heating process, anhydrous ferrous sulphate decomposes into ferric oxide, sulpher dioxide and sulpher trioxide. So, it's a decomposition reaction not a displacement reaction. That's why, the statement of the 'reason' segment is false and incorrectly describes the assertion.

Chemical reaction :

2FeSO4 (anhydrous) + heat -----> Fe2O3 (brown) + SO2 + SO3