Question

Both lithium$\left(\mathrm{Li}\right)$ and magnesium$\left(\mathrm{Mg}\right)$ display several similar properties due to the diagonal relationship; However, the incorrect one is:

• A. Both form nitrides.
• B. Nitrates of both $\mathrm{Li}$ and $\mathrm{Mg}$ yield ${\mathrm{NO}}_2$and ${\mathrm{O}}_2$ on heating.
• C. Both form basic carbonates.
• D. Both form soluble bicarbonates.

Answer 1

The correct option is C

Both form basic carbonates.

Explanation for the correct options:

(C) $\mathrm{Mg}$ forms basic carbonates $\left(3{\mathrm{MgCO}}_3.\mathrm{Mg}{\left(\mathrm{OH}\right)}_2.3{\mathrm{H}}_2\mathrm{O}\right)$ but no such carbonates are formed by $\mathrm{Li}$

Explanation for the incorrect options:

(A) $\mathrm{Li}\mathrm{and}\mathrm{Mg}$ combine directly to form ${\mathrm{Li}}_3{\mathrm{N}}_2$ and ${\mathrm{Mg}}_3{\mathrm{N}}_2$.

(B) Nitrites of $\mathrm{Li}\mathrm{and}\mathrm{Mg}$ yield ${\mathrm{NO}}_2\mathrm{and}{\mathrm{O}}_2$on heating.

${\mathrm{LiNO}}_3\stackrel{∆}{\to }{\mathrm{Li}}_2\mathrm{O}+{\mathrm{NO}}_2+{\mathrm{O}}_2$

$\mathrm{Mg}{\left({\mathrm{NO}}_3\right)}_2\stackrel{∆}{\to }\mathrm{MgO}+{\mathrm{NO}}_2+{\mathrm{O}}_2$

(D) Bicarbonates of Lithium $\left(\mathrm{Li}\right)$ and Magnesium $\left(\mathrm{Mg}\right)$ are more soluble in water than carbonate whereas carbonate of alkali metal is more soluble.

Hence option (C) is correct.