Question 66

A chemist has 10 litres of a solution that is 10 per cent nitric acid by volume. He wants to dilute the solution to 4 per cent strength by adding water. How many litres of water must he add?

Solution

The chemist has 10 litres of solution of which 10% is nitric acid i.e remaining 90% is water.

Now he wants to dilute it to 4% from 10% by adding water.

Let x be the total water added. Then 4% of nitric acid should become 4% of total solution after adding 'x' litres of water.

Now equation can be written as,

1L = 4 % of (10 + x)

25 = 10 + x (or) x = 15L

Hence, option A is the correct answer.

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