(A) $(i)$ $C_{6}H_{6}$: There are $6$ $C-C$ $\sigma$ bonds,$6$ $C-H$ $\sigma$ bonds,and $3$ $\pi$ bonds.
$(ii)$ $C_{6}H_{12}$: There are $6$ $C-C$ $\sigma$ bonds and $12$ $C-H$ $\sigma$ bonds.
$(iii)$ $CH_{2}Cl_{2}$: There are $2$ $C-H$ $\sigma$ bonds,$2$ $C-Cl$ $\sigma$ bonds,and $2$ $C-H$ $\sigma$ bonds (total $4$ $\sigma$ bonds).
$(iv)$ $CH_{2}=C=CH_{2}$: There are $4$ $C-H$ $\sigma$ bonds,$2$ $C-C$ $\sigma$ bonds,and $2$ $\pi$ bonds.
$(v)$ $CH_{3}NO_{2}$: There are $3$ $C-H$ $\sigma$ bonds,$1$ $C-N$ $\sigma$ bond,$1$ $N-O$ $\sigma$ bond,and $1$ $N=O$ $\pi$ bond.
$(vi)$ $HCONHCH_{3}$: There are $4$ $C-H$ $\sigma$ bonds,$1$ $N-H$ $\sigma$ bond,$1$ $C-N$ $\sigma$ bond (in $C-N$),$1$ $C-N$ $\sigma$ bond (in $C-NH$),$1$ $C-O$ $\sigma$ bond,and $1$ $C=O$ $\pi$ bond.