JEE Main levelSingle correct optionDifficulty 2 of 3rg073
Two gases have the following van der Waals constants: gas X, a=5.5, b=0.030; gas Y, a=1.4, b=0.065 (usual units). Which statement is correct?
AX has stronger intermolecular attraction and larger molecular size than Y
BX has stronger intermolecular attraction but smaller molecular size than Y
CY has stronger intermolecular attraction and larger molecular size than X
DY has stronger intermolecular attraction but smaller molecular size than X
Answer: B
a measures attraction and b measures molecular size (excluded volume). X has the larger a (stronger attraction) but the smaller b (smaller molecules). Therefore option B is correct.