Question

Q.39 An industrial solvent of 90% strength is prepared and
stored in a 150 L capacity container. The container is
filled to 80% of its capacity. It is required to decrease
the concentration of the solvent in the container
to less than 60%. For doing this, either pure water
can be added to it and/or solution can be removed.
But removal can only be done if there is no place
for adding water. At a given time, only 10 L of the
solution can be added or removed. How many times
should water be added to the solution?
(a) 4
(C) 9 (d) 6
(b) 5​

Answer 1

Explanation:

Q.39 An industrial solvent of 90% strength is prepared and

stored in a 150 L capacity container. The container is

filled to 80% of its capacity. It is required to decrease

the concentration of the solvent in the container

to less than 60%. For doing this, either pure water

can be added to it and/or solution can be removed.

But removal can only be done if there is no place

for adding water. At a given time, only 10 L of the

solution can be added or removed. How many times

should water be added to the solution?