Explanation:

- Water vapour is the most abundant gas in volcanic eruptions.

- It typically makes up a significant portion of the gas emitted by volcanoes.

- Sulphur Dioxide is present in volcanic emissions.

- However, it's less abundant compared to water vapour.

- Carbon Dioxide is also a common volcanic gas.

- But again, it usually appears in smaller amounts than water vapour.

- Hydrogen Sulphide can be found in volcanic gases.

- Its concentration is typically much lower than that of water vapour.