Calculate the molarity of NaOH in the solution prepared by dissolving its 4 g in enough water to form 250 mL of the solution.

Explanation

Since molarity (M)
`=("No. of moles of solute")/("volume of solution in litres")`
`= ("Mass of NaOH /molar mass of NaOH")/(0.250 L)`
`=(4g//40g)/(0.250 L) = (0.1 "mol")/(0.250 L) = 0.4 "mol" L^(-1) = 0.4 M`