Question

The vapour pressure of pure benzene `C_(6)H_(6)` at `50^(@)C` is `268 "torr"`. How many moles of non-volatile solute per mole of benzene is required to prepare a solution of benzene having a vapour pressure of `167 "torr"` at `50^(@)C`?
A. 0.377
B. 0.605
C. 0.623
D. 0.395

Answer 1

Correct Answer - B
`{:(P_("benzene")^@=268 "torr"),(" "P_(sol)=167 "torr"):}}=chi_B=(268-167)/268=0.377,chi_B=n_B/(n_A+n_B)`
`rArr n_B/n_A=0.605`