Question

$(NH_4)_2Cr_2O_7$ on heating liberates a gas. The same gas will be obtained by

• A. treating $H_2O_2\ \text{with}\ NaNO_2$
• B. heating $NH_4NO_3$
• C. treating $Mg_3N_2 \ \text{with}\ H_2O$
• D. Heating $NH_4NO_2$

Answer 1

Answer: (D)

Heating $NH_4NO_2$

Answer 2

The decomposition of $\text{(NH}_4\text{)}_2\text{Cr}_2\text{O}_7$ on heating liberates nitrogen gas (N2) along with water vapor and chromium(III) oxide $\text{Cr}_2\text{O}_3$. Therefore, the gas liberated from this reaction is N2.
Among the given options:
(A) Treating $\text{H}_2\text{O}_2$ with $\text{NaNO}_2$ does not produce nitrogen gas. It results in the formation of water and oxygen gas.
(B) Heating $\text{NH}_4\text{NO}_3$ decomposes it into nitrogen gas, water, and oxygen gas. However, this is not the same gas obtained from the decomposition of $\text{(NH}_4\text{)}_2\text{Cr}_2\text{O}_7$, which produces N2.
(C) Treating $\text{Mg}_3\text{N}_2$ with H2O produces ammonia gas (NH3), not nitrogen gas.
(D) Heating $\text{NH}_4\text{NO}_2$ decomposes it into nitrogen gas, water, and oxygen gas. This is the correct option.
Therefore, the gas obtained by heating $\text{NH}_4\text{NO}_2$ is the same gas liberated from the decomposition of $\text{(NH}_4\text{)}_2\text{Cr}_2\text{O}_7$, which is nitrogen gas (N2). So, the correct answer is option (D) Heating $\text{NH}_4\text{NO}_2$