Question

5. Identify the substance which continues to burn in an atmosphere of ${\mathrm{N}}_2$.

• A. $\mathrm{Fe}$
• B. $\mathrm{Mg}$
• C. $\mathrm{Cu}$
• D. $\mathrm{W}$

Answer 1

The correct option is B

$\mathrm{Mg}$

Explanation for correct option:

(B): Magnesium $\left(\mathrm{Mg}\right)$ is a reactive metal and reacts with oxygen $\left({\mathrm{O}}_2\right)$ present in the air.

• The reaction involved is: $\underset{\mathrm{Magnesium}}{2\mathrm{Mg}}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2}\to \underset{\mathrm{Magnesium}\mathrm{oxide}}{2\mathrm{MgO}}$
• It catches fire when reacts with air and continues to burn in an atmosphere of nitrogen $\left({\mathrm{N}}_2\right)$.

Explanation for incorrect options:

(A): Iron $\left(\mathrm{Fe}\right)$ reacts with oxygen to Iron oxide $\left({\mathrm{Fe}}_2{\mathrm{O}}_3\right)$.

• The reaction involved is: $\underset{\mathrm{Iron}}{4\mathrm{Fe}}+\underset{\mathrm{Oxygen}}{3{\mathrm{O}}_2}\to \underset{\mathrm{Iron}\mathrm{oxide}}{2{\mathrm{Fe}}_2{\mathrm{O}}_3}$

(C): Copper $\left(\mathrm{Cu}\right)$ reacts with oxygen to Copper oxide $\left(\mathrm{CuO}\right)$, which is black in color.

• The reaction involved is: $\underset{\mathrm{Copper}}{2\mathrm{Cu}}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2}\to \underset{\mathrm{Copper}\mathrm{oxide}}{2\mathrm{CuO}}$

(D): Tungsten $\left(\mathrm{W}\right)$ is an unreactive metal so, it does not react with oxygen.

Hence, option (B) is the correct answer. $\mathrm{Mg}$ continues to burn in an atmosphere of ${\mathrm{N}}_2$.