Question

What mass of sodium hydroxide is present in a `40%` `"m/m"` solution of `"sodium hydroxide"`?

Answer 1

Unknown on these data....we need the density of the solution....

Explanation:

We gots a `40%` solution of sodium hydroxide in water....

i.e. `"mass of sodium hydroxide"/"mass of solution"xx100%=40%`

We need the density of the solution to approach its concentration in `"moles per litre"`.