$(i)$ $\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\ 
  {C{H_3} - {C^ \mathbf{-} }} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}} 
\end{array}$

$(ii)\;\;CH_2 = CH -\stackrel{\mathbf{-}}{C}H_2$

$(iii)\;\;CH \equiv  \stackrel{\mathbf{-}}{C}$

$(iv)\;\;\stackrel{\mathbf{-}}{C}H_3$

$(v)\;\;\stackrel{\mathbf{-}}{C}N$