Chemical Changes and Reactions — Question 6

(a) Gas is evolved

Zn(s) + H₂SO₄ (aq) ⟶ ZnSO₄ (aq) + H₂ (g)

(b) Colour change is noticed

$\underset{\text{ iron}}{\text{Fe}} + \underset{\text{ blue sol.}}{\text{CuSO}_4} \text{ (aq.)} \longrightarrow \underset{\text{ green sol.}}{\text{FeSO}_4} + \underset{\text{ copper-brown red deposit}}{\text{Cu}}$

(c) Precipitate is formed

$\underset{\text{ ferrous sulphate}}{\text{FeSO}_4 \text{ (aq.)}} + \underset{\text{ sodium hydroxide}}{2\text{NaOH}\text{ (aq.)}} \longrightarrow \underset{\text{ dirty green ppt.}}{\text{Fe(OH)}_2↓} + \underset{\text{ sodium sulphate}}{\text{Na}_2\text{SO}_4\text{ (aq.)}}$

(d) Physical state of reactants is changed

C (s) + 2S (s) ⟶ CS₂ (l)