Question

The critical temperature of some gases are: Methane 190K, ammonia 405K, carbon dioxide 304K, n-butane 425K and dihydrogen 33K. The gas that is adsorbed to the maximum extent on 1g of activated charcoal at a given temperature is

• A. dihydrogen
• B. methane
• C. carbon dioxide
• D. n-butane
• E. ammonia

Answer 1

The Correct Option is D

The extent of adsorption of a gas on activated charcoal increases with the critical temperature of the gas. The critical temperature is the temperature above which a gas cannot be liquefied, regardless of pressure. Gases with higher critical temperatures are more easily liquefied and are adsorbed to a greater extent.

Given the critical temperatures:
- Methane: 190K
- Ammonia: 405K
- Carbon dioxide: 304K
- n-Butane: 425K
- Dihydrogen: 33K

Among these, n-butane has the highest critical temperature (425K), which means it is the gas that will be adsorbed to the maximum extent on activated charcoal at a given temperature.

The correct option is (D) : n-butane

Answer 2

The extent of adsorption of a gas on a solid (like activated charcoal) is influenced by the gas's critical temperature. Gases with a lower critical temperature are more easily liquefied and therefore more readily adsorbed by the surface of solids like activated charcoal. This is because at a given temperature, gases with lower critical temperatures are more likely to condense into a liquid phase, increasing their tendency to be adsorbed.  

Among the given gases, dihydrogen has the lowest critical temperature (33K). As a result, it will be adsorbed to the maximum extent on activated charcoal at the given temperature. 

Therefore, the correct answer is n-butane.