sblock Elements 2 Question 6
6. Magnesium powder burns in air to give
(2019 Main, 9 April I)
(a) MgO and $\mathrm{Mg}_3 \mathrm{~N}_2$
(b) $\mathrm{Mg}\left(\mathrm{NO}_3\right)_2$ and $\mathrm{Mg}_3 \mathrm{~N}_2$
(c) MgO only
(d) MgO and $\mathrm{Mg}\left(\mathrm{NO}_3\right)_2$
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Answer:
Correct Answer: 6. (a)
Solution: Magnesium powder burns in air to give MgO and $\mathrm{Mg}_3 \mathrm{~N}_2 . \mathrm{MgO}$ does not combine with excess oxygen to give any superoxide. Mg reacts with nitrogen to form magnesium nitride $\left(\mathrm{Mg}_3 \mathrm{~N}_2\right)$.
$ \begin{gathered} \mathrm{Mg}+\mathrm{O}_2 \longrightarrow \mathrm{MgO} \\ 3 \mathrm{Mg}+\mathrm{N}_2 \longrightarrow \mathrm{Mg}_3 \mathrm{~N}_2 \end{gathered} $
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