States of Matter

A closed vessel contains 10 g of an ideal gas X at 300 K, which exerts 2 atm pressure. At the same temperature, 80 g of another ideal gas Y is added to it and the pressure becomes 6 atm. The ratio of root mean square velocities of X and Y at 300 K is

1. 2 2 : 3
2. 2 2 : 1
3. 1 : 2
4. 2 : 1