A chemistry teacher needs to make 10 liters of 42% sulphuric acid solution. The acid solutions available are 30% sulphuric acid and 50% sulphuric acid, by volume. How many liters of each solution must be mixed to make the 42% solution?

4 liters of 30% and 6 liters of 50% acid.

Step-by-step explanation:

Let the volume of 30% acid be x, then the volume of 50% acid will be

(10 - x) liters.

So we have the equation:

0.30x + 0.50 (10 - x) = 0.42 * 10

0.30x + 5 - 0.50x = 4.2

0.80 = 0.20x

x = 4 liters.

So we need 4 liters of 30% acid and 6 liters of 50% acid.