pBlock ElementsII 1 Question 8
8. The compound that does not produce nitrogen gas by the thermal decomposition is
(2018 Main)
(a) $\mathrm{Ba}\left(\mathrm{N} _{3}\right) _{2}$
(c) $\mathrm{NH} _{4} \mathrm{NO} _{2}$
(b) $\left(\mathrm{NH} _{4}\right) _{2} \mathrm{Cr} _{2} \mathrm{O} _{7}$
(d) $\left(\mathrm{NH} _{4}\right) _{2} \mathrm{SO} _{4}$
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Answer:
Correct Answer: 8. (d)
Solution:
- The thermal decomposition of given compounds is shown below
$ \begin{gathered} \left(\mathrm{NH} _{4}\right) _{2} \mathrm{Cr} _{2} \mathrm{O} _{7} \stackrel{\Delta}{\longrightarrow} \mathrm{N} _{2}+4 \mathrm{H} _{2} \mathrm{O}+\mathrm{Cr} _{2} \mathrm{O} _{3} \\ \mathrm{NH} _{4} \mathrm{NO} _{2} \stackrel{\Delta}{\longrightarrow} \mathrm{N} _{2}+2 \mathrm{H} _{2} \mathrm{O} \\ \left(\mathrm{NH} _{4}\right) _{2} \mathrm{SO} _{4} \stackrel{\Delta}{\longrightarrow} 2 \mathrm{NH} _{3}+\mathrm{H} _{2} \mathrm{SO} _{4} \\ \mathrm{Ba}\left(\mathrm{N} _{3}\right) _{2} \longrightarrow \mathrm{Ba}+3 \mathrm{N} _{2} \end{gathered} $
Thus, only $\left(\mathrm{NH} _{4}\right) _{2} \mathrm{SO} _{4}$ does not gives $\mathrm{N} _{2}$ on heating (It give $\mathrm{NH} _{3}$ ). While rest of the given compounds gives $\mathrm{N} _{2}$ on their thermal decomposition.
