The depression in freezing point of `0.01 m` aqueous `CH_(3)COOH` solution is `0.02046^(@)`, `1 m` urea solution freezes at `-1.86^(@)C`. Assuming molality equal to molarity, `pH` of `CH_(3)COOH` solution is

Options

A. 2
B. 3
C. 3.2
D. 4.2

Answer

B

Explanation

`DeltaT_(f)=K_(f) xx m xx i`
`(DeltaT(urea))/(DeltaT(CH_(3)COOH))=(m'(urea))/(m'(CH_(3)COOH)xx1)`
`i=1.1 (i=1 for urea)`
`=(1 + x)` for` CH_(3)COOH`
`x=0.1`
`:. [H^(o+)] = Cx =0.001`
`:. pH=3`