Question

The noble gas which behaves abnormally in liquid state is :

• A. Xe
• B. Ne
• C. He
• D. Ar

Answer 1

Answer: (C)

He

Gaseous $He$ on cooling below 4.18K changes to liquid known as $He\left(I\right)$ which on cooling to 2.2 K and 1 atmospheric pressure changes to an abnormal liquid known as $He\left(II\right)$. $He\left(II\right)$ liquid behaves as a gas and hence this state of liquid is said to be fourth state of matter. $He\left(II\right)$ behaves as superfluid and hence abnormal state. $He\left(I\right)$ is a normal liquid.