Question

`6.02 xx 10^(20)` molecules of urea are present in 100 mL of its solution. The concentration of urea solution is
(Avogadro constant, `N_(A) = 6.02 xx 10^(23)mol^(-1))`
A. `0.001 M`
B. `0.1M`
C. `0.002M`
D. `0.01`

Answer 1

Correct Answer - D
In 100 mL no. of molecules of urea `=6.02xx10^(20)`
`therefore` No. of urea molecules in 1000 mL of solution
`= 6.02xx10^(20)xx10`
`= 6.02xx10^(21)`
`therefore` No. of moles of urea in 1 L
`=(6.02xx10^(21))/(6.02xx10^(23))=10^(-2)mol`
`therefore` Concentration of solution `= 10^(-2)M`
`= 0.01M`