Question

Which one of the following molecules is paramagnetic ?

• A. $N_2$
• B. NO
• C. CO
• D. $O_3$

Answer 1

Answer: (B)

The molecular orbital configuration of the molecules given is Total no. of electrons in NO

$=7(N)+8(0)=15$

Hence E.C. of NO

$=K{\left[\sigma \left(2s\right)\right]}^2{\left[{\sigma }^{\ast }\left(2s\right)\right]}^2{\left[\sigma 2p_z\right]}^2$

${\left[\pi \left(2p_x\right)\right]}^2{\left[\pi \left(2p_y\right)\right]}^2{\left[{\pi }^{\ast }\left(2p_x\right)\right]}^1$

Due to presence of one unpaired electron NO is paramagnetic Except NO all are diamagnetic due to absence of unpaired electrons