Molarity of solution containing 8 g of NaOH in 200 mL solution is
(molar mass of NaOH : 40 g mol–1)
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 1 M
Molarity is the number of moles of solute dissolved in one litre of solution:
\( \displaystyle M = \frac{\text{moles of solute}}{\text{volume of solution in L}} \)
\( \displaystyle \text{Moles of NaOH} = \frac{8\ \mathrm{g}}{40\ \mathrm{g\,mol^{-1}}} = 0.2\ \mathrm{mol} \)
\( \displaystyle M = \frac{0.2\ \mathrm{mol}}{0.200\ \mathrm{L}} = 1\ \mathrm{mol\,L^{-1}} = 1\ \mathrm{M} \)
Note: NTA picked this question from an NCERT (2026-27) example and changed the figures. Do not ignore NCERT while practising numericals.
NCERT (2026-27 edition):
Expressing Concentration of Solutions – “Example 1.2: Calculate the molarity of a solution containing 5 g of NaOH in 450 mL solution.”