Arrange the following gases in increasing order of van der Waals constant 'a' A. Ar B. $$\mathrm{CH}_{4}$$ C. $$\mathrm{H}_{2} \mathrm{O}$$ D. $$\mathrm{C}_{6} \mathrm{H}_{6}$$ Choose the correct opti

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Q61

Arrange the following gases in increasing order of van der Waals constant 'a' A. Ar B.

\mathrm{CH}_{4}

\mathrm{H}_{2} \mathrm{O}

\mathrm{C}_{6} \mathrm{H}_{6}

Choose the correct option from the following.

A D, C, B and A

B A, B, C and D

C B, C, D and A

D C, D, B and A

Correct Answer

Option B

Solution

The van der Waals constant 'a' is a measure of the strength of the intermolecular forces in a gas.

Larger molecules and molecules with stronger intermolecular forces will have larger 'a' constants.

Here, we are comparing argon (Ar), methane (CH₄), water (H₂O), and benzene (C₆H₆).

Argon (Ar) is a noble gas and is monoatomic.

Methane (CH₄) is a small molecule with weak intermolecular forces.

Water (H₂O) is a small molecule but has strong hydrogen bonding, making its intermolecular forces stronger than those in methane.

Benzene (C₆H₆) is a larger molecule than the others and has relatively strong intermolecular forces due to its larger size and polarizability.

So, in the increasing order of van der Waals constant 'a', it should be: Argon (Ar) < Methane (CH₄) < Water (H₂O) < Benzene (C₆H₆)