Calculate the normality of an NaOH solution. 21.5 mL of which is required to convert 0.240 g of a ${\mathrm{NaH}}_2{\mathrm{PO}}_4$ in a solution to monohydrogen phosphate

Normality of an NaOH solution in the given condition can be calculated as,

$\mathrm{N}\times \frac{21.5}{1000}=\frac{0.240}{120}$

N x 21.5 = 0.240/ 1000 120

N =0.093 N

Thus, option B is correct.