JEE Main · 2022 · Shift-ImediumMOLE-108

A commercially sold conc. HCl is 35\% HCl by mass. If the density of this commercial acid is 1.46\,g/mL, the molarity…

Some Basic Concepts (Mole Concept) · Class 11 · JEE Main Previous Year Question

Question

A commercially sold conc. HCl is $35\%$ HCl by mass. If the density of this commercial acid is $1.46\,\text{g/mL}$ , the molarity of this solution is: (Atomic mass: Cl $= 35.5$ , H $= 1\,\text{amu}$ )

Options

a
$10.2\,\text{M}$
b
$14.0\,\text{M}$
✓
c
$12.5\,\text{M}$
d
$18.2\,\text{M}$

Correct Answerb

$14.0\,\text{M}$

Detailed Solution

🧠 The mass-percent-to-molarity formula $M = \frac{10 \times d \times \%}{M_w}.$

This compresses the volume-and-mass conversion into one line.

🗺️ Plug in $d = 1.46\,\text{g/mL}$ , $\% = 35$ , $M_w(\ce{HCl}) = 36.5\,\text{g/mol}$ .

$M = \frac{10 \times 1.46 \times 35}{36.5} = \frac{511}{36.5} \approx 14.0\,\text{M}.$

⚡ Quick mental math $1.46 \times 25 = 36.5$ . So $1.46 / 36.5 = 1/25 = 0.04$ . Then $M = 10 \times 0.04 \times 35 = 14$ .

$\boxed{\text{Answer: (b)}}$

Practice this question with progress tracking

Want timed practice with adaptive difficulty? Solve this question (and hundreds more from Some Basic Concepts (Mole Concept)) inside The Crucible, our adaptive practice platform.

Practice in The Crucible →Browse Some Basic Concepts (Mole Concept) chapter →

More JEE Main Some Basic Concepts (Mole Concept) PYQs

2025medium

At the sea level, the dry air mass percentage composition is given as nitrogen gas: 70.0, oxygen gas: 27.0 and argon gas: 3.0. If total pressure is 1.15 atm, then calculate the ratio of followings…

2025easy

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) 45 (b) 55…

2024medium

Molality (m) of 3\,M aqueous solution of NaCl is: (Density = 1.25\,g mL-1; Mr: Na = 23, Cl = 35.5)

2024medium

The density of "x M" solution of NaOH is 1.12\,g mL-1, while in molality, the concentration of the solution is 3\,m (3 molal). Then x is: (Molar mass of NaOH = 40\,g/mol)

2023easy

A solution is prepared by adding 2\,g of X to 1 mole of water. Mass percent of X in solution is:

View all 57 Some Basic Concepts (Mole Concept) PYQs →