Question

A barometer the liquid-1 with density 2 Kg/m^3 and height 5 cm below the outside level and above that liquid-2 with density 0.5 Kg/m^3 and length 10 cm, what is the gauge pressure of the gas?

(a) 0.01 Pa

(b) 0.05 Pa

(c) 0.1 Pa

(d) 0.5 Pa

I had been asked this question during an interview for a job.

This is a very interesting question from Differential Pressure Measurements topic in chapter Temperature and Pressure of Basic Chemical Engineering

Answer 1

Right answer is (d) 0.5 Pa

To explain: Gauge pressure of gas + Pressure of liquid-2 = Pressure of liquid-1, => Gauge pressure of gas = 2*10*0.05– 0.5*10*0.1 = 0.5 Pa.