The paramagnetic behaviour of `B_2` is due to the presence of

Options

A. 2 unpaired electrons in `pi_b MO`
B. 2 unpaired electrons in `pi^(**) MO`
C. 2 unpaired electrons in `sigma^** MO`
D. 2 unpaired electrons in `sigma_b MO`

Answer

A

Explanation

`B_2` (electrons = 10)
`sigma(1s)^2, sigma^**(1s)^2, sigma(2s)^2 , sigma^** (2s)^2, pi (2p_x)^1, pi (2pi_y)^1`
Thus paramagnetic behaviour of `B_2` is due to the presence of two unpaired electrons in `pi -` bonding molecular orbital.