The value \(\gamma = \dfrac{C_P}{C_V}\) for hydrogen, helium, and another ideal diatomic gas \(X\) (whose molecules are not rigid but have an additional vibrational mode), are respectively equal to:
1. \(\dfrac{7}{5}, \dfrac{5}{3}, \dfrac{9}{7}\)
2. \(\dfrac{5}{3}, \dfrac{7}{5}, \dfrac{9}{7}\)
3. \(\dfrac{5}{3}, \dfrac{7}{5}, \dfrac{7}{5}\)
4. \(\dfrac{7}{5}, \dfrac{5}{3}, \dfrac{7}{5}\)