Question

A container contains 10 litres mixture in which there is 10% sulphuric acid. How much sulphuric acid is to be added to make the solution to contain 25% sulphuric acid?

• A. 2 litres
• B. 1 litre
• C. 4 litres
• D. Data inadequate
• E. None of these

Answer 1

The correct option is A 2 litres

Given that 1 litre of sulphuric acid is already present in the 10 litres mixture
Let $x$ litres of sulphuric acid be added to the mixture, so that the volume of the new mixture becomes $10+x$ litres

According to question,
$25=\frac{x+1}{10+x}\times 100$
$10+x=4x+4$
$x=2$
Hence 2 litres of sulphuric acid should be added.