Question

1 mole of each of $X_1,X_2$ and $X_3$, with van der Waals’ constant ‘$a$’ (in $\left({\text{atm L}}^2{\text{mol}}^{(-2)}\right)$ 1.0, 3.8 and 2.1, respectively are kept separately in three different vessels of equal volume at the same temperature. Their pressures are observed to be $P_1,P_2$, and $P_3$ respectively. On the basis of this data alone, select the correct option (neglect the effect of ‘$b$’):

• A. $P_1<P_2<P_3$
• B. $P_2<P_1<P_3$
• C. $P_2<P_3<P_1$
• D. $P_1=P_2=P_3$

Answer 1

The correct option is C $P_2<P_3<P_1$

'a' representsn the attraction between molecules. Lower the value of 'a', lower will be internal reduction in pressure and greater will be the observed P. Hence, $X_2$ has the least P and $X_1$ has the highest P.