Question

Activity of a pure element in its standard state is:

• A. 0
• B. 1
• C. \(\infty\)
• D. -1

Hint:

Remember: The activity of any pure substance in its standard state is defined as 1, whether it's a solid, liquid, or gas.

Answer 1

The Correct Option is B

In thermodynamics and chemical equilibrium calculations, the activity of a substance is a measure of its "effective concentration".
For a pure element in its standard state (which is its most stable form at 1 bar pressure and a specified temperature, typically 298 K), its activity is defined as 1.
This simplification allows us to focus on relative activities of other substances without having to assign a value to a pure substance in standard conditions.
Therefore, the activity of a pure element in its standard state is always taken as 1.