of gas A diatomic molecule is 29 & 22 J mol-1 K-1 respt. Another gas B of diatomic molecule has corresponding value 30 & 20 J mol-1 K-1 respt. If they are treated as ideal gas then.
A has a vibration mode B has none
A has one vibration mode B has two
A is rigid but B has vibration mode
Both A and B has a vibration mode.