Question

Given below a statement (S) and explanation (E) is given. Choose the appropriate answer:

Statement (S): $O_2$ is diamagnetic

Explanation (E): $O_2$ has two electrons in anti-bonding $\pi$ orbitals.

• A. S is correct but E is wrong
• B. S is wrong but E correct
• C. Both S and E are correct and E is correct explanation of S
• D. Both S and E are correct but E is not correct explanation of S

Answer 1

The correct option is B

S is wrong but E correct

Now, here our first step is to check whether statement 1 and is right.

So, let's draw MOT energy level diagram for oxygen molecule.

Eelctronic configuration of $O_2$ is:

$O_2$$⟶$ $(\sigma 1s{)}^2$ $({\sigma }^{\ast }1s{)}^2$ $(\sigma 2s{)}^2$ $({\sigma }^{\ast }2s{)}^2$ $(\sigma 2p_z{)}^2$ $(\pi 2p_{x^2}\equiv \pi 2p_{y^2})$ $({\pi }^{\ast }2p_{x^2}\equiv {\pi }^{\ast }2p_{y^2})$

Therefore, we have two unpaired electrons in ${\pi }^{\ast }2p_x$ and ${\pi }^{\ast }2p_y$, therefore it will be PARAMAGNATIC.

STATEMENT I is wrong

Now,

STATEMENT II is right.

Because $O_2$ has two electrons in anti-bonding $\pi$ orbitals