On the basis of the data given below, the gas which shows the least adsorption on a definite amount of charcoal is-

Gas

CO2

SO2

CH4

H2

Critical temp./K

304

630

190

33

1. CO2
2. SO2
3. CH4
4. H2

HINT: Lesser the value of the critical temperature of gases lesser will be the extent of adsorption
Explanation: 
Lesser the value of the critical temperature of gases lesser will be the extent of adsorption. Here H2 has the lowest value of critical
temperature,i.e.  33 K.  Hence, hydrogen gas shows the least adsorption on a definite amount of charcoal.