The total number of covalent bonds formed in the Lewis structures of given species respectively are:

(a) ${\mathrm{CO}}_3^{2-}$

(b) ${\mathrm{CCl}}_4$

(c) ${\mathrm{NF}}_3$

(d) ${\mathrm{HNO}}_3$

Consider the following statements:

${\mathrm{S}}_1$: ${\mathrm{N}}_2{\mathrm{H}}_4$ is pyramidal about each $\mathrm{N}$ atom.

${\mathrm{S}}_2$: ${\mathrm{NH}}_2\mathrm{OH}$ is pyramidal about the $\mathrm{N}$ atom and bent about the $\mathrm{O}$ atom.

${\mathrm{S}}_3$: ${\mathrm{CH}}_3\mathrm{COCl}$ is trigonal about the carbon atom (attached to $\mathrm{O}$ and $\mathrm{Cl}$).

Out of these, select the correct one.