3 molal solution of NaOH means 3 moles of NaOH are dissovled in 1 kg solvent So. The mass of solution =1000g solvent +120g NaOH=1120g solution
(Molar mass of `NaOH=23+16+1=40g` and 3 moles of NaOH`=3xx40=120g`)
Volume of solution `=("Mass of solution")/("Density of solution") ( because d=(m)/(V))`
`V=(1120g)/(1.110g mL^(-1))=1009mL`
Molarity`=("Moles of solute"xx1000)/("volume of solution"(mL))`
`=(3xx100)/(1009)=2.973M=3M`