The density of a solution prepared by dissolving 120 g of urea (mol. Mass=60 u) in 1000 g of water is 1.15 g/mL. The molarity if this solution is

Options

A. 1.78 M
B. 1.02 M
C. 2.05 M
D. 0.50 M

Answer

C

Explanation

Total mass of the solution = 120 + 1000 = 1120 g
Volume of the solution = Mass/density
`=(1120g)//1.15g mL^(-1)=974mL`
Molarity (M) `= ("Mass of solute/Molar mass")/("Volume of solution in litres")`
`=((120g)//("60 g mol"^(-1)))/(("974/1000 L"))`
`=2.05"mol L"^(-1)=2.05 M`.