Given below are two statements. One is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : Activated charcoal adsorbs SO₂ more efficiently than CH₄.
Reason R : Gases with lower critical temperatures are readily adsorbed by activated charcoal.
In the light of the above statements, choose the correct answer from the options given below.

Solution

Chemistry ma’am · 3 steps

Higher critical temperature means easier to liquefy, and that means stronger adsorption.

1. What decides adsorption. Charcoal holds gases by physical adsorption, through weak van der Waals forces. A gas with a higher critical temperature has stronger intermolecular forces and liquefies more easily, so it is adsorbed more.

   Gas	Critical temperature	Adsorption on charcoal
   SO₂	about 430 K, high	more
   CH₄	about 190 K, low	less

2. Check each statement. Assertion A is correct because SO₂ is adsorbed more than CH₄. Reason R has the trend backwards: gases with lower critical temperatures are adsorbed less, not more readily.
3. So. A is correct and R is not, so the answer is (c).

The idea to keep. For physisorption, the easier a gas liquefies, the more it is adsorbed. Higher critical temperature means more adsorption: SO₂ and NH₃ beat CH₄ and H₂.

Answer from the NTA final answer key. Solution by PrepWiser.