Question

the morality of 4% NAOH solution is???

Answer 1

40% m/m or 40% m/v or 40% v/v solution? 
Im considering it to be a 40% m/m solution. The answer might vary for m/v and v/v.

40% m/m solution of NaOH means 100g water has 40g NaOH
So, number of moles of NaOH= 40/molar mass of NaOH
=40/40
=1

Molality = number of moles of solute/mass of solvent (in kg)
= no. of moles of NaOH/ mass of water
= 1/(100×0.001)
= 10 molal