# DBT JRF 2022 — Question 7

Exam: DBT JRF 2022 · Section: B · Topic: Biochemistry › Solution Dilutions & Concentration · Difficulty: Medium

## Question

What will be the final concentration of the solute when 10 ml of its 10 M solution is mixed with 990 ml solvent?

## Options

- **A.** 1 M
- **B.** 0.1 M
- **C.** 10 M
- **D.** 0.001 M

## Answer

Option B

## Explanation

Dilution using $C_1V_1 = C_2V_2$ : Given: 10 mL of 10 M solution mixed with 990 mL solvent. Total final volume = 10 + 990 = 1000 mL = 1 L Applying the dilution equation: $C_1 V_1 = C_2 V_2$ $10\,\text{M} \times 10\,\text{mL} = C_2 \times 1000\,\text{mL}$ $C_2 = \frac{100}{1000} = 0.1\,\text{M}$ Alternatively: Dilution factor = $\frac{1000}{10} = 100$ , so concentration decreases 100-fold: $\frac{10}{100} = 0.1\,\text{M}$ . Answer: 0.1 M (Option 2).

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