Question

What is the average mass of a substance with specific gravity 10, and its volume varies with time as V = t/500, from t = 2, to t = 0 seconds? (Density of water = 1000 kg/m^3)

(a) 25

(b) 20

(c) 40

(d) 75

I had been asked this question during an online exam.

This is a very interesting question from Specific Gravity topic in section Moles, Density & Concentration of Basic Chemical Engineering

Answer 1

Correct answer is (b) 20

The best explanation: Density of substance = 10 * 1000 = 10000 kg/m^3, => mass of substance = 10000*t/500 = 20t, => average mass = (1/2)∫20t = 5t^2 = 5(2^2 – 0^2) = 20.