Which from following compounds is obtained when phenol reacts with dilute nitric acid at low temperature?

In the equation, $\mathrm{BiO}_3^{-}+6 \mathrm{H}^{+}+x \mathrm{e}^{-} \rightarrow \mathrm{Bi}^{3+}+3 \mathrm{H}_2 \mathrm{O}$ What is the value of $x$ ?

The compound forming ccp structure contains $9.6 \times 10^{23}$ atoms. Find the number of tetrahedral voids formed in it.

Identify a pair of molecules having similar shapes of both members.