JEE Main 202522 JanuaryEvening Shift
- Exam
- JEE Main
- Year
- 2025
- Date
- 22 January
- Shift
- Evening Shift
- Subject
- Chemistry
- Chapter
- Some Basic Concepts of Chemistry
JEE Main 2025 · 22 January · Evening Shift · Chemistry · Some Basic Concepts of Chemistry
Density of 3 M NaCl solution is 1.25 ~g / mL . The molality of the...
Density of 3 M NaCl solution is . The molality of the solution is :
Options
- A1.79 m
- B2.79 m
- C2 m
- D3 m
Correct answer
B. 2.79 m
Step-by-step solution
\begin{aligned} & 3 \mathrm{M} \mathrm{NaCl}, \mathrm{d}_{\text{sol }}=1.25 \mathrm{gm} / \mathrm{mol} \\ & \begin{aligned} \text{ Molality } & =\frac{\mathrm{M} \times 1000}{1000 \mathrm{ d}-\mathrm{M} \times \mathrm{M}_{\mathrm{W}}} \\ & =\frac{3000}{1250-175.5}=2.79\end{aligned}\end{aligned}$