Half a litre of a solution contains 15% alcohol. To change the alcohol concentration to 50%, find the quantity of alcohol to be m…

Question

Half a litre of a solution contains 15% alcohol. To change the alcohol concentration to 50%, find the quantity of alcohol to be mixed.

1. A. 400 ml
2. B. 350 ml (Correct answer)
3. C. 175 ml
4. D. 250 ml

Correct Answer

Option B — 350 ml

Detailed Solution & Explanation

The correct answer is 350 ml.

Key Points

• 500 ml contains $15\%$ alcohol $=75$ ml. Let $x$ ml of alcohol be added.
• $\dfrac{75+x}{500+x}=\dfrac{50}{100}\Rightarrow 150+2x=500+x\Rightarrow x=350$ ml.