Two ballons are filled, one with pure He gas and other by air, repectively. If the pressure and temperature of these ballons are same then the number of molecules per unit volume is:

Options

A. more in the He filled balloon
B. same in both ballons
C. more in air filled balloon
D. in the ratio of 1:4

Answer

B

Explanation

Ideal gas equation can be written as
pV=nRT ….. (i)
In this equation ,
n= number of moles of the gas
p= pressure of the gas
V = volume of the gas
R= universal gas constant
and T = temperature of the gas
from Eq . (i) , We have , `(n)/(V)=(P)/(RT)="constant"`
So , at constant pressure and temperature , both balloons will contain equal number of molecules per unit volume.