Phase terminology – partial evaporation and the definition of steam Evaluate the statement: “The state of a substance whose evaporation from its liquid state is partial is known as steam.”

Introduction / Context:
Correct naming of phase states prevents misinterpretation of property tables. Partial evaporation produces a two-phase mixture; we must distinguish this from a pure vapor state and from the special term “steam.”

Given Data / Assumptions:

• Substance has both liquid and vapor present (wet condition).
• Equilibrium at a given pressure–temperature pair on the saturation dome.
• Engineering usage of the word “steam” is considered.

Concept / Approach:
When evaporation is partial, the state is a saturated liquid–vapor mixture (wet state). For water, the term “wet steam” is used, but “steam” by itself generally signifies water vapor, often dry saturated or superheated. The statement claiming “steam” as the generic name for any partial evaporation is therefore inaccurate.

Step-by-Step Solution:
Identify the state: partial evaporation → two-phase mixture.Name the state correctly: saturated mixture (wet region) with quality x between 0 and 1.Clarify terminology: “steam” commonly refers to the vapor phase of water; “wet steam” specifies a mixture, not a pure state.Conclude the given statement is false as written.

Verification / Alternative check:
Steam tables differentiate saturated liquid, saturated vapor (dry steam), and wet mixture with defined quality x; the terminology supports the distinction.

Why Other Options Are Wrong:

• Conditional agreements do not fix the categorical misuse; the correct generic term is “saturated mixture,” not simply “steam.”

Common Pitfalls:
Using “steam” ambiguously; always specify wet, dry saturated, or superheated to avoid confusion.

Final Answer:
Disagree