A glass tube of volume 112ml. containing a gas is partially evacuated till the pressure in it drops to 3.8×10−5  torr at 00C . The number of molecules of the gas remaining in the tube is

n=PVRT             =3.8760×10−5×112100022.4273×273             =14×10−9 ∴  number of molecules =nN                                                =14×10−9×6×1023                                                =1.5×1014