1)

What is the bond order of B2  molecule ?


A) 3

B) 0

C) 1

D) 2

Answer:

Option C

Explanation:

  The bond order of B2  molecule is 1. The ground  state electron configuration  of  B is 1s2 2s22p1.So, B2 molecule has a total of ten electrons, which are arranged  in MO s.

$(\sigma1s)^{2}(\sigma^{*}1s)^{2}(\sigma2s)^{2}(\sigma^{*}2s)^{2}(\pi_{2p_y^1}=\pi_{2p_y^1})$

  Bond order = $\frac{1}{2}$ (Number of bonding electrons - Number of anti-bonding electrons )

=$\frac{1}{2}(6-4)=1$