A `0.1` molal aqueous solution of a weak acid is `30%` ionized. If `K_(f)` for water is `1.86^(@)C//m`, the freezing point of the solution will be.

Options

A. `-0.36^(@)C`
B. `-0.24^(@)C`
C. `-0.18^(@)C`
D. `-0.54^(@)C`

Answer

B

Explanation

`DeltaT_(f)=iK_(f)m`
`HArarrH^(+)+A^(-)`
`1-alpha alpha alpha`
`1-0.3 0.3 0.3`
`i=1-0.3+0.3+0.3`
`i=1.3`
`DeltaT_(f)=1.3xx1.86xx0.1=0.2418`
`T_(f)=0-0.2418=-0.2418^(@)C`