The molecular orbital theory supports paramagnetic behavior of

Options

A. `"Be"_(2)`
B. `"C"_(2)`
C. `"N"_(2)`
D. `"O"_(2)`

Answer

D

Explanation

When all the electrons in a molecule are paired it is diamagnetic and when unpaired electrons are present it is paramagnetic.
Considering the filling of electrons in molecular orbitals the e.c. of molecules is
`Be_(2)(8)=(sigma1s)^(2),(sigma^(*)1s)^(2),(sigma2s)^(2),(sigma""^(*)2s)^(2)`
`C_(2)(12)=(sigma1s)^(2),(sigma^(*)1s)^(2),(sigma2s)^(2),(sigma^(*)2s^(2))(pi2p_(y))^(2),(pi 2p_(z))^(2)`
`N_(2)(14)=(sigma1s)^(2),(sigma^(*)1s)^(2),(sigma2s)^(2),(sigma^(*)2s)^(2)(pi 2p_(y))^(2),(pi 2p_(z))^(2),(sigma 2p_(x))^(2)`
`O_(2)(16)=(sigma1s)^(2),(sigma^(*)1s)^(2),(sigma2s)^(2),(sigma^(*)2s)^(2)(pi 2p_(y))^(2),(sigma2p_(x))^(2)(pi2p_(z))^(1)(pi2p_(z))^(1)`
Unpaired electron is present only in `O_(2)`, so it is paramagnetic.