5.0 g of sodium hydroxide `("molar mass 40 g mol"^(-1)) is dissolved in little quanitity of water and the solution is diluted upto 100 mL. What is the molarity of the resulting solution ?

Options

A. `0.1"mol dm"^(-3)`
B. `1.0"mol dm"^(-3)`
C. `0.125"mol dm"^(-3)`
D. `1.125"mol dm"^(-3)`

Answer

D

Explanation

Molarity is given as,
`M=("Moles of solute")/("Volume of solution (in L)")`
`M=(Wxx1000)/("m" xx "volume of solution (in mL")`
Given, W (mass of solute) =5.0g
m (molar mass of solute) = 40 g `mol^(-1)`
Volume =100 mL
`M=(5.0gxx1000)/(40xx100)`
`1.25" mol dm"^(-3)`