Question

Magnesium burns in air to give:
(A) $MgO and Mg$
(B) $Mg{{O}_{2}}andM{{g}_{3}}{{N}_{2}}$
(C) $M and M{{g}_{3}}{{N}_{2}}$
(D) $M{{g}_{2}}OandM{{g}_{3}}{{N}_{2}}$

Answer 1

Hint: The two major constituent gases of the air are nitrogen and oxygen. Therefore, the burning of magnesium in the air should result in the production of compounds obtained when it will react with these two respective gases. Find out the products formed between the reaction of magnesium with oxygen and nitrogen.

Complete step by step solution:
Given that,
Magnesium burns in air.
So, having seen the hint as given above, magnesium reacts with two gases that are present in the air. Let us now look at the reaction between magnesium and oxygen. This reaction may be referred to as a combustion reaction, as it will give heat and light. The balanced chemical reaction is as follows:
\[2M{{g}_{(s)}}+{{O}_{2(g)}}\xrightarrow{\Delta }2Mg{{O}_{(s)}}\]
So, the product of this reaction is magnesium oxide, whose chemical formula is \[MgO\].
Let us now observe the balanced chemical reaction between magnesium and nitrogen,
$3M{{g}_{(s)}}+{{N}_{2(g)}}\xrightarrow{\Delta }M{{g}_{3}}{{N}_{2(s)}}$
So, we can see that the product formed by the reaction between magnesium and nitrogen is magnesium nitride, whose chemical formula is $M{{g}_{3}}{{N}_{2}}$.
The formation of other compounds like carbonates, nitrates and nitrites are not possible, because the atmospheric combustion of any substance is simply a reaction with oxygen. Magnesium nitride formed in this case is so because of the abundances of nitrogen gas in the atmosphere and we know that, in the atmosphere, substances like carbonates, nitrates and nitrites are not found in concentration that could intervene in any reaction happening in the surrounding.
Thus, the products formed are $M and M{{g}_{3}}{{N}_{2}}$.

Hence, the correct option is C.

Note: Magnesium is a metal with the atomic number and is placed in the second group of the Periodic table. It reacts violently with water, so the reaction of magnesium with water is avoidable. Magnesium burning in the air is a type of exothermic reaction as it gives heat and light.