Answer: 20 liters
Step-by-step explanation:
Let x liter of 10% hydrogen peroxide solution is mixed with y liter of 25% hydrogen peroxide solution to create 30 liters of a 15% hydrogen peroxide solution.
Thus, Total quantity of mixture = 30
⇒ x + y = 30 ---------(1)
And, Total quantity of hydrogen in the mixture is the sum of total quantity of hydrogen in x liter and y liter,
⇒ 10 % of x +25 % of y = 15 % of 30
⇒ 10 x + 25 y = 450
⇒ 2 x + 5 y = 90 ------- (2)
Equation (2) - 2× Equation (1),
⇒ 3 y = 30
⇒ y = 10
Substitute this value in equation (1),
We get,
x + 10 = 30
⇒ x = 20,
Hence, the quantity of 10% solution chemist used to make the 15% solution = x liter = 20 liter.
