How is water classified in its vapor phase?

• A. As a solid
• B. As a liquid
• C. As steam
• D. As ice

Answer: (C)

Water in its vapor phase is classified as steam. This classification is based on the physical state of water at high temperatures where it transitions from liquid to gas. When water is heated beyond its boiling point, it evaporates and enters the vapor phase, forming steam. Steam consists of tiny water molecules that are spread far apart and move freely, indicating that they are in a gaseous state.

The other options represent different states of water; for example, ice is the solid form and occurs at temperatures below freezing. Liquid water is the state we commonly encounter at moderate temperatures. Only steam correctly describes the gaseous form of water when it is in its vapor phase.