Question

Among $K{O}_2,Al{O}_2^{-},Ba{O}_2,andN{O}_2^{+}$, unpaired electron is present in:

• A. $K{O}_2$ and $Ba{O}_2$ both
• B. neither $K{O}_2$ nor $Ba{O}_2$
• C. $K{O}_2$ only
• D. $Ba{O}_2$ only

Answer 1

Answer: (C)

$K{O}_2$ only

Superoxide ($K{O}_2$) is paramagnetic. It contains $O_2^{+}$ ion. The electronic configuration of the $O_2^{+}$ containing 15 electrons can be written as:

$1s^2\ast 1s^{2}2s^2\ast 2s^{2}2p{z}^{2}2p{x}^{2}2p{y}^2\ast 2p{x}^1$.

It has one unpaired electron.

$Ba{O}_2$ has $O_2^{+2}$ ion. The electronic configuration of the $O_2^{+2}$ containing 14 electrons can be written as:

$1s^2\ast 1s^{2}2s^2\ast 2s^{2}2p{z}^{2}2p{x}^{2}2p{y}^2$.

It is diamagnetic as it has 0 unpaired electrons.