Question

We have a jar filled with gas characterised by parameters P, V and T and another jar B filled with a gas with parameters 2P, V/4,2T; where the symbols have their usual meanings. The ratio of the number of molecules of jar A to those of jar B is?

(a) 1:1

(b) 1:2

(c) 2:1

(d) 4:1

The question was asked during a job interview.

I'm obligated to ask this question of Ideal Gases topic in portion Kinetic Theory of Gases of Engineering Physics I

Answer 1

The correct answer is (d) 4:1

The explanation is: n1 r=PV/T

n2 r=(2P)(V/2)/2T=PV/4T=1/4 n1 r

n1/n2 = 4/1=4:1.