Q.29. The pressure of interstellar space is about 4.0 atm. If the temperature is 3 K, how many molecules are present per litre?
(R = 0.08 l-atm/K-mol)
According to the gas law:
P = 4 x 10-22 atm.
T = 3 K
V is to considered as unity as no. of molecules is to be calculated per unit volume.
Putting these values:
As 1 mol = 6 x 1023 molecules.
50/3 x 10-22 mol will contain = 6 x 1023 x 50/3 x 10-22 molecules
= 100.2 x 10
= 1002 molecules
So, 1002 molecules are present per unit volume of the interstellar space.
So, the option ( d ) is correct .