A graph is plotted between `PV_(m)` along Y-axis and `P` along X-axis whre `V_(m)` is the molar voulume of a real gas Find the intercept along Y-axis .

Explanation

For real gases, van der Waals' equation for 1 mole is
`[P+(a)/(V_(m)^(2))][V_(m) -b] =RT`
or `PV_(m) - Pb-+ (a)/(V_(m)) - (ab)/(V_(m)^(2)) = RT`
or `PV_(m) =RT +Pb - (a)/(V_(m)) + (ab)/(V_(m)^(2))...(1)`
The intercept of graph between `PV_(m) vs P` will mean that at `P =0 i. e, V_(m)` tends to `oo` Thus neglecting `(a)/(V_(m))`
and `(ab)/(V_(m)^(2))` terms in eq (1)
or `PV_(m) =RT +Rb`
when `P=0` intercept `=RT`
Thus a graph between `PV_(m) vs P` will lead to an intercept `RT` eq (2) represents is a straight line equation `(y = mx +c)`
.