The vapour pressure of two liquids 'P' and 'Q' are 80 and 60 torr respectively. The total vapour pressure of solution obtained by mixing 3 mole of P and 2 mol of Q would be

Options

A. 68torr
B. 140torr
C. 48torr
D. 72torr

Answer

D

Explanation

`"moles of "X,n_(x)=(3)/(3+2)=(3)/(5)`
`"Moles of "Y,n_y=(2)/(3+2)=(2)/(5)`
`p_(T)=p_(x)n_(x)+p_(y)n_(y)=80xx(3)/(5)+60xx(2)/(5)," "p_(T)=72"torr"`