Question

An unsteady-state system, with 10 liters as initial amount of water in the vessel, water flow in rate is 8 liters/ s and flow out rate is 5 liters/s, what will be the amount of water in the vessel after 10 seconds?

(a) 10 liters

(b) 20 liters

(c) 30 liters

(d) 40 liters

I have been asked this question during a job interview.

The question is from Steady-State and Unsteady-State Systems topic in division Introduction to Material Balances of Basic Chemical Engineering

Answer 1

The correct answer is (d) 40 liters

The best I can explain: Amount of water added to the vessel in 10 seconds = (8 – 5)*10 = 30 liters, => Final amount of water = 10 + 30 = 40 liters.