Question

A chemist mixes two liquids 1 and 2. One litre of liquid 1 weighs 1 kg and one litre of liquid 2 weighs 800 gm. If half litre of the mixture weighs 480 gm, then the percentage of liquid 1 in the mixture, in terms of volume, is

• A. 85
• B. 70
• C. 75
• D. 80

Answer 1

The Correct Option is D

Weight per liter of liquid 1 = 1000 gm 
Weight per liter of liquid 2 = 800 gm 
Weight per liter of the mixture = \( \frac{2 \times 480}{1+1} = 960 \) gm

Using the allegation rule:

We find the ratio of quantities of liquid 1 and liquid 2 as: \[ \frac{960 - 800}{1000 - 960} = \frac{160}{40} = \frac{4}{1} \]

So, the liquids are mixed in the ratio 4:1.

Percentage of Liquid 1 in the mixture:

\[ \frac{4}{4+1} \times 100 = \frac{4}{5} \times 100 = 80\% \]

 Final Answer: \( \boxed{80\%} \)