Molality of a solution in aqueous medium is `0.8`. Calculate its more fraction and the percentage by mass of solute if molar mass of solute is `60`

Options

A. `4.5%`
B. `4.6%`
C. `4.7%`
D. `4.8%`

Answer

A

Explanation

We know that
`m= (x_(B)xx1000)/((1-x_(B))xxm_(A))`…(i)
where,`x_(B)` =mole fraction of solute
`m_(A)` = molar mass of solvent
`0.8=(x_(B)xx1000)/((1-x_(B))xxm_(A))`
`x_(B)=0.014`
Let`w_(B)=xg,w_(a)=100g`
`m=(w_(b)xx1000)/(60xxw_(A))`
`0.8=(x xx1000)/(60xx100)`
`x=4.8%`