Answer the question on the basis of passage given below:
Adsorption is a surface phenomenon which can be expressed by means of an empirical relationship known as Freundlich Adsorption isotherm. The relationship is given by
\(\frac{x}{m} = Kp^{\frac{1}{n}}\left(n > 1\right)\)
\(x = \) Mass of the gas adsorbed
\(m = \) Mass of adsorbent
\(p = \) Pressure at which adsorption takes place
\(K\) and \(n\) are constant
| Gas | \(C_2H_6\) | \(SO_2\) | \(Cl_2\) | \(H_2\) |
| Critical Temperature (in K) | 210 | 630 | 243 | 33 |
On the basis of given data which one of the following gases shows maximum adsorption on a definite amount of charcoal
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \(SO_2\)
Physical adsorption of a gas on charcoal is due to van der Waals forces, the same forces that cause liquefaction. Gases that are easily liquefiable, i.e. have a higher critical temperature, are adsorbed more readily. Among the four gases \( \ce{SO2} \) has the highest critical temperature (630 K), so a given amount of charcoal adsorbs the largest amount of \( \ce{SO2} \).
Order of adsorption: \( \ce{SO2} \) (630 K) > \( \ce{Cl2} \) (243 K) > \( \ce{C2H6} \) (210 K) > \( \ce{H2} \) (33 K).
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Nature of Adsorbate
