Question

Which of the following statements is true for a paramagnetic substance?

• A. These substances are weakly attracted by an external magnetic field, due to presence of the unpaired electrons.
• B. These substances are strongly attracted by an applied magnetic field and can be permanently magnetised.
• C. $NaCl,KCl$ are examples of paramagnetic substances
• D. (a) and (c) above.

Answer 1

The correct option is A These substances are weakly attracted by an external magnetic field, due to presence of the unpaired electrons.

Paramagnetic substance:
All those atoms and molecules, which have an odd number of electrons, are paramagnetic. These substances are weakly attracted by an external magnetic field, due to presence of these unpaired electrons.
Paramagnetic substances are magnetised in the same direction as the magnetic field. They lose magnetism in the absence of magnetic field.


Ferromagnetism:
It is a property by which a substance can show permanent magnetism even in the absence of the magnetic field. Such substance are known as ferromagnetic substances.
These substances are strongly attracted by an applied magnetic field and can be permanently magnetised.

Diamagnetic substances:
Diamagnetic substances do not have any unpaired electrons. All the electrons gets paired up so their magnetic moments gets cancel with each other.
$H_{2}O,NaCl,KCl,C_6{H}_6,Ti{O}_2$ are examples of diamagnetic substances.