Calculate the molarity of a solution containing 5g of NaOH in 450 mL solution.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 0.278 M
Molarity is the number of moles of solute in one litre of solution.
Molar mass of NaOH = 23 + 16 + 1 = 40 g mol−1
\( \displaystyle \text{Moles of NaOH} = \frac{5\ \text{g}}{40\ \text{g mol}^{-1}} = 0.125\ \text{mol} \)
\( \displaystyle \text{Volume of solution} = 450\ \text{mL} = 0.450\ \text{L} \)
\( \displaystyle \text{Molarity} = \frac{0.125\ \text{mol}}{0.450\ \text{L}} = 0.278\ \text{mol L}^{-1} = 0.278\ \text{M} \)
Note: This question is from NCERT (2026-27). NTA sets numerical questions from NCERT too, so do not ignore NCERT while practising numericals.
NCERT (2026-27 edition):
Expressing Concentration of Solutions – …
