Which of the following is diamagnetic?

Options

A. superoxide ion
B. carbon molecule
C. unipositive ion of nitrogen molecule
D. oxygen molecule

Answer

B

Explanation

Carbon molecule `(C_2)` with `12e^(-)s` is diamagnetic. Though `O_2` has `16e^(-)s`, but it is paramagnetic due to the presence of two unpaired `e^(-)s` in the antibonding `pi MOs`. Superoxide ion `(O_2^(-))` is also paramagnetic as it has one unpaired `e^(-)`. Nitrogen molecule `(N_2)` is diamagnetic but `N_2^(+)` is paramangnetic due to one unpaired electron.