JEE Main 2025 · 28 January · evening · Single correct · +4 / −1
Concentrated nitric acid is labelled as 75 % by mass. The volume in mL of the solution which contains 30 g of nitric acid is ______________.
Given : Density of nitric acid solution is 1.25 g / mL.
- (a) 32
- (b) 40
- (c) 55
- (d) 45
Answer and solution
Answer (a) 32
Solution
Chemistry ma’am · 3 steps
Go from acid to solution by mass first, then use density to turn that mass into volume.
- Mass of solution. 75% by mass means 75 g of HNO₃ in every 100 g of solution. So 30 g of acid needs 30 × 100/75 = 40 g of solution.
- Mass to volume. Density links the mass of the solution to its volume. Divide the mass by the density.
V = m/d = (40 g)/(1.25 g mL⁻¹) = 32 mL
- So. The volume of solution that contains 30 g of nitric acid is 32 mL, option (a).
The idea to keep. Mass percent always refers to the mass of the whole solution, and density belongs to the solution too. Find the solution's mass first, then divide by density.
Answer from the NTA final answer key. Solution by PrepWiser.