5.0 g of sodium hydroxide (molar mass 40 g `mol^(-1)`) is dissolved in little quantity of water and 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. 1.25 mol `dm^(-3)`

Answer

D

Explanation

Molarity = `(W_(2)/(M_(2) xxV(dm^(3))))`
`=(5g)/(40 g "mol"^(-1) xx V("dm")^(3))`
`=1.25 mol dm^(-3)` (`therefore 100 mL = 0.1 L = 0.1 dm^(3))`