question_answer 1)

  Gases possess characteristic critical temperature which depends upon the magnitude of intermolecular forces between the particles. Following are the critical temperatures of some gases :  

Gases	\[{{H}_{2}}\]	\[He\]	\[{{O}_{2}}\]	\[{{N}_{2}}\]
Critical temperature in kelvin	33.2	5.3	154.3	126

  From the above data what would be the order of liquefaction of these gases? Start writing the order from the gas liquefying first : (a) \[{{H}_{2}}.He,{{O}_{2}},{{N}_{2}}\]        (b) \[He,{{O}_{2}},{{H}_{2}},{{N}_{2}}\]                           (c) \[{{N}_{2}},{{O}_{2}},He,{{H}_{2}}\]        (d) \[{{O}_{2}},{{N}_{2}},{{H}_{2}},He\]

Answer:

  (d) The gas with greater critical temperature involvesstronger intermolecular force hence liquefied first. \[\frac{\underset{{{T}_{c}}}{\mathop{{}}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\underset{154.3K}{\mathop{{{O}_{2}}}}\,\,\,\,\,\,\,\,\,\underset{126K}{\mathop{{{N}_{2}}}}\,\,\,\,\,\,\,\,\,\,\underset{33.2K}{\mathop{{{H}_{2}}}}\,\,\,\,\,\,\,\,\,\,\,\,\,\underset{5.3K}{\mathop{He}}\,}{\text{Decreasing}\,\text{tendency}\,\text{of}\,\text{liquefaction}}\]