• # question_answer a and b are van der Waals constants for gases. Chlorine is more easily liquefied than ethane because A)  a for $C{{l}_{2}}>a$ a for ${{C}_{2}}{{H}_{6}}$ but b for $C{{l}_{2}}<b$for ${{C}_{2}}{{H}_{6}}$ B)  a and b for $C{{l}_{2}}>a$ and b for ${{C}_{2}}{{H}_{6}}$ C)  a and b for $C{{l}_{2}}<a$ a and b for ${{C}_{2}}{{H}_{6}}$ D)  a for $C{{l}_{2}}<a$ for ${{C}_{2}}{{H}_{6}}$ but b for $C{{l}_{2}}>b$ for ${{C}_{2}}{{H}_{6}}$

The van der Waals constant a is a measure of forces of attraction between gaseous molecules. Larger the value of a, the more easily the gas can be liquefied. Since $C{{l}_{2}}$ is more easily liquefied than ethane, it follows that $a(C{{l}_{2}})>a({{C}_{2}}{{H}_{6}})$ The van der Waals constant b is a measure of effective volume occupied by gaseous molecules. Larger the size of the molecule, larger the value of b. Since ${{C}_{2}}{{H}_{6}}$ seems to be larger in size than $C{{l}_{2}},$ it follows that $b(C{{l}_{2}})<b({{C}_{2}}{{H}_{6}}).$