Which of the following is the convenient way of expressing concentration when a solute is present in trace quantities?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Parts per million
NCERT (2026-27 edition):
1.2 Expressing Concentration of Solutions – “(iv) Parts per million: When a solute is present in trace quantities, it is convenient to express concentration in parts per million (ppm) and is defined as:
\( \displaystyle \text{Parts per million}=\frac{\text{Number of parts of the component}}{\text{Total number of parts of all components of the solution}}\times10^{6} \qquad (1.3) \)”