The vapour pressure of two liquid P and Q are 80 torr and 60 torr respectively. The total vapour pressure obtained by mixing `3` moles of P and 2 mole of Q would be

Options

A. 140 torr
B. 20 torr
C. 68 torr
D. 72 torr

Answer

D

Explanation

`xp=3/(3 +2) = 3/5 , xQ = 2/(3 + 2)=2/5`
`:. "Total" V.P. = (xP xx p_(p)^(o)) + (xQ xx p_(Q)^(0))`
`V.P. = (3/5 xx 80) + (2/5 xx 60 ) = 48 + 24 = 72 "torr"`