What is the number of chiral carbon atoms present in 2-chloro-3,4-dimethylhexane?

Which of the following is a primary amine?

The $\mathrm{E}_{\text {cell }}^{+}$of $\mathrm{Cu}_{(\mathrm{s})}\left|\mathrm{Cu}_{(\mathrm{1M})}^{++} \| \mathrm{Ag}_{(\mathrm{1M})}^{+}\right| \mathrm{Ag}_{(\mathrm{s})}$ is 0.647 volt. Calculate the $\mathrm{E}_{\mathrm{Ag}}^{\circ}$ if $\mathrm{E}_{\mathrm{Cu}}^{\circ}$ is 0.153 V .

Conjugate acid of $\mathrm{NH}_2^{-}$and $\mathrm{NH}_3$ are respectively