Question

Nitric acid cannot be concentrated beyond ___ % by the distillation of a dilute solution of $HN{O}_3$.

• A. 48
• B. 86
• C. 6.8
• D. 68

Answer 1

The correct option is D 68

Nitric acid forms a constant boiling mixture with water containing 68% acid.

This mixture boils constantly at the constant boiling point $\left({121}^{\circ }C\right)$ without any change in its composition.

At this temperature, the gas and the water vapour escape together. Hence, the composition of the solution remains unchanged.

That is why, nitric acid cannot be concentrated beyond 68% by the distillation of dilute solution of $HN{O}_3$.