Answer:
The assertion is incorrect, and the reason provided is also incorrect.
Step-by-step explanation:
Water vapor (H2O in its gaseous state) is not a chemical compound. It is the gaseous form of water, which is a compound composed of hydrogen and oxygen. The chemical formula for water is H2O, indicating that it consists of two hydrogen atoms bonded to one oxygen atom.
The reason provided is also incorrect. The ratio of hydrogen to oxygen in water, by mass, is approximately 1:8. However, this ratio refers to the composition of water itself, not water vapor. Water vapor is simply the gaseous form of water and does not have a fixed ratio of hydrogen to oxygen.
Therefore, the assertion is incorrect, and the reason provided is also incorrect.