Question

Jackie has two solutions that are $2$ percent sulphuric acid and $12$ percent sulphuric acid by volume respectively. If these solutions are mixed in appropriate quantities to produce $60$ litres of a solution that is $5$ percent sulphuric acid, approximately how many litres of the $2$ percent solution will be required?

• A. $18$
• B. $20$
• C. $24$
• D. $36$
• E. $42$

Answer 1

Answer: (E)

$42$

Let Volume of Solution $1$ be $V_1$ and Volume of Solution $2$ be $V_2$

Now, $5\%$ of $60$ litres $=3$ litres of Sulphuric Acid

Let us calculate the volume of sulphuric acid contributed by solution $1$ and solution $2$ to this $3$ litres

$\Rightarrow 3=\frac{12\times V_2}{100}+\frac{2\times V_1}{100}$

$\Rightarrow 300=12V_2+2V_1$..........................(1)

Also, $V_1+V_2=60$(Total Volume of Solution).........................(2)

Comparing (1) and (2) we get

$\Rightarrow V_1=42,V_2=18$

Therefore Answer is $\left(E\right)$