Question

A gas at one atmosphere and having volume 100ml is mixed with another gas of equal moles at 0.5atm and having volume 50ml in flask of one litre, what is the final pressure?

(a) 0.5atm

(b) 1atm

(c) 0.75atm

(d) 0.125atm

I have been asked this question in an online interview.

My enquiry is from Ideal Gases in section Kinetic Theory of Gases of Engineering Physics I

Answer 1

Correct choice is (d) 0.125atm

The best I can explain: Total number of moles is conserved.

(P1 V1)/RT+(P2 V2)/RT=PV/RT

(1×100)/RT+(0.5×50)/RT=(P×1000)/RT

P=0.125atm.