Question

The weight in grams of a non-volatile solute $(M.wt:60)$ to be dissolved in $90g$ of water to produce a relative lowering of the vapour pressure of $0.02$ is:

• A. $4$
• B. $8$
• C. $6$
• D. $10$

Answer 1

Answer: (C)

$6$

Formula to be used, :

$\frac{\Delta P}{P^o}=\frac{w\times M}{m\times W}$

$0.02=\frac{w\times 18}{60\times 90}$

$w=\frac{0.02\times 60\times 90}{18}=0.02\times 60\times 5=0.02\times 300=6$