Chemistry · Some Basic Concepts of Chemistry (Mole Concept) + Stoichiometry

JEE Main 2025 — 28 January, Morning Shift — Question 47

The molarity of a $70\%$ (mass/mass) aqueous solution of a monobasic acid $(X)$ is $\_\_\_\_\_$ M (nearest integer).

[Given: density of solution $=1.25\ \mathrm{g\ mL^{-1}}$ , molar mass of acid $=70\ \mathrm{g\ mol^{-1}}$ ]

Answer: 13

Numerical answer — enter this value.

Assume $100\ g$ solution.

Mass of acid $= \mathrm{70\ g}$

Moles $= \mathrm{\frac{70}{70} = 1\ mol}$

Density relation, $\mathrm{volume = \frac{mass}{density}}$ $= \mathrm{\frac{100}{1.25} = 80\ mL = 0.08\ L}$

Molarity, $\mathrm{M = \frac{1}{0.08} = 12.5}$

Thus, the nearest integer is $\mathrm{13}$ .

Answer key and solution verified before publishing.

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