Question

Consider the following statements: If the Vander Waal's parameters of two gases are given as an (atm lit${}^2$ mol${}^{-2}$) b(lit mol${}^{-1}$)

Gas X : 6.5 0.056 Gas Y: 8.0 0.011 then a: V${}_c$(X) < V${}_c$(Y)

b: P${}_c$(X) < P${}_c$(Y)
c: T${}_c$(X) < T${}_c$(Y) select correct alternate

• A. a alone
• B. a and b
• C. a, b and c
• D. b and c

Answer 1

The correct option is D b and c

If the vander Waal's parameters of two gases are given as a(atm lit${}^2$ mol${}^{-2}$) b(lit mol${}^{-1}$)
Gas X : 6.5 0.056 Gas Y: 8.0 0.011 then a: V${}_c$(X) < V${}_c$(Y)
b: P${}_c$(X) < P${}_c$(Y)
c: T${}_c$(X) < T${}_c$(Y)
Then the correct alternate statements are b and c.
The vander waals constant a represents magnitude of attractive forces between the molecules. Greater is the value of a, more easily the gas can be liquefied and lower will be the critical pressure.
The vander waals constant b represents the effective size of gas molecules. Greater is the value of b, larger is the size and smaller is the compressible volume. Hence, the critical volume of X will be larger than the critical volume of Y and the critical temperature of X will be smaller than the critical temperature of Y.