Question

A cylinder completely filled with water has density = 10 kg/m^3 and volume 5 m^3 , now a cube with side 1 m and density 25 kg/m^3 is dipped into the cylinder with some water dropping out, what is the final density of cylinder?(neglect the mass of cylinder)

(a) 13 kg/m^3

(b) 15 kg/m^3

(c) 17 kg/m^3

(d) 19 kg/m^3

I had been asked this question in a job interview.

Question is from Density topic in chapter Moles, Density & Concentration of Basic Chemical Engineering

Answer 1

Right choice is (a) 13 kg/m^3

Easy explanation: Initial mass of cylinder = 10*5 = 50 kg, mass of cube = 25*1 = 25 kg, => mass of water coming out = 10*1 = 10 kg, => final density of cylinder = (50 + 25 – 10)/5 = 13 kg/m^3.