Among the given group $14$ elements,the one with highest density is

Which pair of elements can form multiple bonds with itself and oxygen?

In the following reaction,assign the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$: $\underline{C}O + H_2O \longrightarrow \text{No reaction}$

Find $A$,$B$ and $C$ in the following reactions:
$NH_3 + A + CO_2 \rightarrow (NH_4)_2CO_3$
$(NH_4)_2CO_3 + H_2O + B \rightarrow 2NH_4HCO_3$
$NH_4HCO_3 + NaCl \rightarrow NH_4Cl + C$

Silicon chloroform is prepared by

Inert pair effect is predominant in