Match List-I with List-II.
| List-I | List-II |
| (A) Mass percentage | (p) \(\frac{\text{Number of moles of solute}}{\text{Volume of solution in litres}}\) |
| (B) Molality | (q) \(\frac{\text{Number of moles of a component}}{\text{Total number of moles of all the components}}\) |
| (C) Mole fraction | (r) \(\frac{\text{Mass of the component in the solution}}{\text{Total mass of the solution}} \times 100\) |
| (D) Molarity | (s) \(\frac{\text{Number of moles of solute}}{\text{Mass of solvent in kilograms}}\) |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → A-r, B-s, C-q, D-p
Each List-II expression is the defining ratio of one concentration term.
(A) Mass percentage — This matches (r). It is the mass of the component divided by the total mass of the solution, multiplied by 100.
(B) Molality — This matches (s). It counts moles of solute per kilogram of solvent, not per litre of solution.
(C) Mole fraction — This matches (q). It is the moles of one component divided by the total moles of all the components, so it has no unit.
(D) Molarity — This matches (p). It counts moles of solute per litre of solution.
NCERT (2026-27 edition):
1.2 Expressing Concentration of Solutions – “(i) Mass percentage (w/w): The mass percentage of a component of a solution is defined as:
\( \displaystyle \text{Mass }\%\text{ of a component}=\frac{\text{Mass of the component in the solution}}{\text{Total mass of the solution}}\times 100 \qquad (1.1) \)”
“(v) Mole fraction: Commonly used symbol for mole fraction is x and subscript used on the right hand side of x denotes the component. It is defined as:
\( \displaystyle \text{Mole fraction of a component}=\frac{\text{Number of moles of the component}}{\text{Total number of moles of all the components}} \qquad (1.4) \)”
“(vi) Molarity: Molarity (M) is defined as number of moles of solute dissolved in one litre (or one cubic decimetre) of solution,
\( \displaystyle \text{Molarity}=\frac{\text{Moles of solute}}{\text{Volume of solution in litre}} \qquad (1.8) \)”
“(vii) Molality: Molality (m) is defined as the number of moles of the solute per kilogram (kg) of the solvent and is expressed as:
\( \displaystyle \text{Molality (m)}=\frac{\text{Moles of solute}}{\text{Mass of solvent in kg}} \qquad (1.9) \)”