A `6.90 M` solution of KOH in water has 30% by mass KOH. Calculate density of solution.

Options

A. `1.33 g mL ^(-1)`
B. `1.288 g mL ^(-1)`
C. `1.66 g mL ^(-1)`
D. `1.44 g mL ^(-1)`

Answer

B

Explanation

`{:("KOH solution is 30% by mass", therefore "Mass of KOH = 30 g "),(" and Mass of solution =100 g", therefore "Volume of solution=" (100)/(d)):}`
(where d is density of solution)
`therefore` Molarity `=6. 90 = ( 30)/(56 xx (100)/(1000 xx d)) implies d = 1. 288 g mL ^(-1)`