An aqueous solution of a non-volatile non-electrolyte shows a relative lowering of vapour pressure of $0.0200$ (molar mass of water $18$ ). Which statements are correct?

AThe ratio $p / p^{0}$ equals $0.0200$
BThe ratio $n_{solute} / n_{water}$ is about $0.0204$
CThe molality of the solution is about $1.13 m$
DIf the solute has molar mass $100 g mo l^{- 1}$ , then $100 g$ of water holds about $11.3 g$ of solute

Answer: B, C, D

p / p^{0} = 1 - 0.0200 = 0.9800

, so statement 1 is false.

x_{2} / x_{1} = n_{2} / n_{1} = 0.0200/0.9800 = 0.0204

(true). Molality

= 0.0204 \times 1000/18 = 1.134 m

(true). For

100 g

water,

n_{2} = 0.0204 \times 5.556 = 0.1134 mol

, which is

0.11 g

100 g mo l^{- 1}

(true). Answer: 2, 3 and 4.