The molarity of solution containing `15.20 g` of urea, (molar mass = 60) dissolved in `150 g` of water is

Options

A. `1.689 "mol" kg^(-1)`
B. `0.1689` mol `kg^(-1)`
C. `0.5922` mol `kg^(-1)`
D. `0.2533` mol `kg^(-1)`

Answer

A

Explanation

`W_(2) = 15.20g`
`M_(2) = 60g mol^(-1)`
`W_(1) = 150 g`
m = ?
Calculation : To Calculate molality
`m=(W_(2))/(M_(2) xx W_(1)(kg))`
`=(15.20 xx 10^(-3)kg)/(60 xx 10^(-3) kg mol^(-1) xx 150 xx 10^(-3) kg)`
`=(15.20 xx 1000)/(60 xx 150) = (15.2 xx 10)/( 6 xx 15)`
`m=(15.2 xx 10)/(90) = 15.2/9 = 1.689 mol kg^(-1)`