States of Matter (Gaseous and Liquid States)

Both gas A and Hydrogen (H2) gas have same volume at same pressure. Let both 's volume is V and pressure P.
For gas A :
Pressure =P
Temperature(T)=300K
Volume =V
Mass =3g
Molar mass =M‌gm∕mol
using ideal gas equation,
PV=nRT
⇒PV=‌

3

M

×R×300....(1)
For Hydrogen,
Pressure =P
Temperature (T)=200K
Volume =V
Mass =0.2g
Molar mass =2‌gm∕mol
Using ideal gas equation,
PV=‌

0.2

2

×R×200...... (2)
From (1) and (2), we get
‌

3

M

×R×300=‌

0.2

2

×2×200
⇒M=45