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

Explanation

`"Since molarity (M)"`
`("Number of solution in litres(v)")/("Volume of solution in litre (v)")`
`=n=(w)/(MW)=("weight")/("molecular weight")`
`=(4g//40g)/(0.250L)="0.4 mol L"^(-1)=0.4M`