Question

a green salt in heating decomposes it produce a colorless suffocating gas and leaves behind a brown residue . Name the salt and write decomposition reaction, and the colour change you observed

Answer 1

The salt is Ferrous Sulphate which after decomposition formed Iron Oxide (which is brown in colour) crystals with evolution of Sulphur Dioxide and Sulphur Trioxide

$2FeSO_{4}.7H_{2}O$ ⇒ $Fe_{2}O_{3}+SO_{2}+SO_{3}$