JEE Advanced · 2008 · 13 Apr 2008 · Paper 1 · p-Block Elements

A solution of colourless salt

H

on boiling with excess NaOH produces a non-flammable gas. The gas evolution ceases after sometime. Upon addition of Zn dust to the same solution, the gas evolution restarts. The colourless salt(s)

H

is (are)

(A) $NH_{4} NO_{3}$ ✓ Correct
(B) $NH_{4} NO_{2}$ ✓ Correct
(C) $NH_{4} Cl$
(D) $(NH_{4})_{2} SO_{4}$

Answer: (A), (B)

Solution

The non-flammable gas produced is ammonia (

NH_{3}

).

For

NH_{4} NO_{3}

NH_{4} NO_{3} + NaOH ⟶ NH_{3} + NaNO_{3} + H_{2} O

After ammonia evolution ceases, Zn dust reduces the nitrate:

7 NaOH + 2 NaNO_{3} + 4 Zn \to 4 Na_{2} ZnO_{2} + NH_{3} + 2 H_{2} O

For

NH_{4} NO_{2}

NH_{4} NO_{2} + NaOH \to NaNO_{2} + NH_{3} + H_{2} O

3 Zn + 5 NaOH + NaNO_{2} \to 3 Na_{2} ZnO_{2} + NH_{3} + H_{2} O

NH_{4} Cl

and

(NH_{4})_{2} SO_{4}

would only produce ammonia initially, with no restart upon Zn addition.

JEE Advanced · 2008 · 13 Apr 2008 · Paper 1 · One or more correct options

Practise more: all JEE Advanced PYQs on p-Block Elements →

JEE Advanced · 2008 · 13 Apr 2008 · Paper 1 · p-Block Elements

Solution

More JEE Advanced questions on p-Block Elements