\begin{array}{|l|c|c|c|c|}
\hline Molecules & \begin{array}{c}
Total no. \\
of I
\end{array} & \begin{array}{c}
e in bonding \\
orbitals
\end{array} & \begin{array}{c}
e in anti- \\
bonding \\
orbital
\end{array} & \begin{array}{c}
Bond \\
order
\end{array} \\
\hline (a) \mathrm{He}_2 & 4 & 2 & 2 & 0 \\
(b) \mathrm{Be}_2 & 8 & 4 & 4 & 0 \\
(c) \mathrm{Li}_2 & 6 & 4 & 2 & 1 \\
(d) \mathrm{B}_2 & 10 & 6 & 4 & 1 \\
(e) \mathrm{C}_2 & 12 & 8 & 4 & 2 \\
(f) \mathrm{Nee}_2 & 20 & 10 & 10 & 0 \\
\hline
\end{array}