Question

Which one of the following molecules is expected to exhibit diamagnetic behaviour?

• A. $C_2$
• B. $N_2$
• C. $O_2$
• D. $S_2$

Answer 1

Answer: (A), (B)

$N_2$
$C_2$

$C_2(6+6=12)=\sigma 1s^2,{\sigma }^{\ast }1s^2,\sigma 2s^2,{\sigma }^{\ast }2s^2,{\pi }_2{p}_x^2={\pi }_2{p}_y^2$

Since all electrons are paired it is dimagnetic species.

$N_2(7+7=14)$ = $\sigma 1s^2,{\sigma }^{\ast }1s^2,\sigma 2s^2,{\sigma }^{\ast }2s^2,{\pi }_2{p}_x^2={\pi }_2{p}_y^2,{\sigma }_2{p}_z^2$

Since all electrons are paired it is dimagnetic species.

$O_2(8+8=16)$ or $S_2$ = $\sigma 1s^2,{\sigma }^{\ast }1s^2,\sigma 2s^2,{\sigma }^{\ast }2s^2,{\pi }_2{p}_x^2={\pi }_2{p}_y^2,{\sigma }_2{p}_z^2,{\pi }_2^{\ast }{p}_x^1={\pi }_2^{\ast }{p}_y^1$

Since,$O_2$ or $S_2$ contains 2 unpaired electrons therefore they are paramagnetic .

Hence,option A and B is correct answer.