Answer:
Taking into account the table we get that, for n = 2, the velocities of sound waves are
Velocity on air: 267.3 m/s
Velocity on helium: 260 m/s
Velocity of carbon dioxide: 829.3 m/s
The velocity of the sound travels at different speeds in each gas because the velocity depends on the properties of the medium like the density. Since the air, helium, and carbon dioxide have different densities, the sound speed will be different.