Question

the molarity of 2% w/v NaOH solution

Answer 1

This means there are 2g of NaOH in 100 mL of solution.
That would be the same as having 20 g NaOH in 1 L of solution.
Since the molar mass of NaOH is 40 g/mol
20 g NaOH / 40 g/mol NaOH = 0.5 mol NaOH
So, since there is 0.5 mol NaOH in 1 L solution, the solution is 0.5 M