Question

Q4. Dirty green precipitates soluble in excess of ammonium hydroxide are of

• A. Ferrous hydroxide
• B. Ferric hydroxide
• C. Copper hydroxide
• D. Lead hydroxide

Answer 1

The correct option is A

Ferrous hydroxide

Explanation for correct option:

(A) The reaction of ferrous hydroxide in excess of ammonium hydroxide is:

$\underset{\mathrm{Ferrous}\mathrm{sulphate}}{{\mathrm{FeSO}}_4\left(\mathrm{s}\right)}+\underset{\mathrm{ammonium}\mathrm{hydroxide}}{2{\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{l}\right)}\to \underset{\mathrm{Ferrous}\mathrm{hydroxide}}{\mathrm{Fe}{\left(\mathrm{OH}\right)}_2\left(\mathrm{s}\right)}\downarrow +\underset{\mathrm{ammonium}\mathrm{sulphate}}{{\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4\left(\mathrm{s}\right)}$

An explanation for incorrect options:

(B) Ferric hydroxide does not give dirty green precipitates soluble in excess of ammonium hydroxide.

(C) Copper hydroxide forms a blue precipitate in excess of ammonium hydroxide.

(D) Lead hydroxide does not form dirty green precipitates soluble in excess of ammonium hydroxide.

Ferrous hydroxide gives a Dirty green precipitates soluble in excess of ammonium hydroxide. Thus option A is correct.