B 2 molecule will be diamagnetic when : (I) s − p mixing is NOT operative (II) s − p mixing is operative and Hunds rule is violated (III) s − p mixing is operative and Hunds rule is NOT violated

Question

B 2 ​ molecule will be diamagnetic when : (I) s − p mixing is NOT operative (II) s − p mixing is operative and Hunds rule is violated (III) s − p mixing is operative and Hunds rule is NOT violated

TestHub · Accepted Answer

The B₂ molecule has 10 electrons.

If s-p mixing is NOT operative, the molecular orbital configuration is $σ_{1 s}^{2} σ_{1 s}^{* 2} σ_{2 s}^{2} σ_{2 s}^{* 2} π_{2 p}^{4}$ . All electrons are paired, making it diamagnetic.

If s-p mixing IS operative, the configuration is $σ_{1 s}^{2} σ_{1 s}^{* 2} σ_{2 s}^{2} σ_{2 s}^{* 2} π_{2 p}^{2} σ_{2 p}^{0}$ . Hund's rule dictates two unpaired electrons in $π_{2 p}$ orbitals, making it paramagnetic. Thus, for diamagnetism, s-p mixing must NOT be operative.

The final answer is A

Chemistry - CHEMICAL BONDING Question with Solution | TestHub

Options:

Doubts & Discussion