Question

Paramagnetism is shown by the molecules which have:

• A. paired electrons
• B. unpaired electrons
• C. lone pair of electrons
• D. bond order more than one.

Answer 1

Answer: (B)

unpaired electrons

Paramagnetism

Paramagnetism is a form of magnetism whereby certain materials are weakly attracted by an externally applied magnetic field and form internal, induced magnetic fields in the direction of the applied magnetic field.

To calculate the magnetic moment of a molecule:-

The formula used to calculate the spin-only magnetic moment can be written in two forms; the first based on the number of unpaired electrons, $n$, and the second based on the total electron spin quantum number, $S$. Since for each unpaired electron, $n=$1$andS=$1/2$

then the two formulae are clearly related and the answer obtained must be identical.

[1] ${\mu }_m=\sqrt{n(n+2)}$

[2] ${ \mu }_{ m }=\sqrt { 4S(S+1) }$

NOTE= if one molecule has unpaired electrons that it will definitely show paramagnetism.

So the correct option is [B].