NaOH aqueous solution is labeled as 10% (w/v). Density of the solution is 1.02 g/ml. Then the mole fraction of the solute in the solution is

10% - 10g of NaOH in 100mL of solution.

100g of NaOH in 1000mL of solution.

1.02g present in 1mL of the solution

1020g present in 1000mL of the solution.

Mole fraction of solute =$\frac{{\displaystyle \frac{100}{40}}}{{\displaystyle \frac{100}{40}}+{\displaystyle \frac{920}{18}}}=\frac{2.5}{2.5+51.1}=\frac{2.5}{53.6}=0.0466$