Which of the following is an incorrect statement?

Options

A. Most heterogeneous catalytic reactions involve the solid surface of the catalyst
B. Heterogeneous catalyst primarily function by lowering the activation energy of the reaction
C. A solid catalyst present in the power form is more effective as it has large surface area
D. The catalyst may be deactivated by heating it to a high temperature in vacuum

Answer

To determine which of the following statements is incorrect, we will evaluate each option one by one.

### Step 1: Evaluate the First Statement
**Statement:** The most heterogeneous catalytic reaction involves the solid surface of the catalyst.

**Analysis:** This statement is correct. Heterogeneous catalysis typically involves a solid catalyst that provides a surface for the reaction to occur, while the reactants are in a different phase (usually gas or liquid).

### Step 2: Evaluate the Second Statement
**Statement:** Heterogeneous catalysts primarily function by lowering the activation energy of the reaction.

**Analysis:** This statement is also correct. Catalysts work by providing an alternative pathway for the reaction with a lower activation energy, thereby increasing the reaction rate.

### Step 3: Evaluate the Third Statement
**Statement:** A solid catalyst present in powder form is more effective; it has a larger surface area.

**Analysis:** This statement is correct as well. A powdered solid catalyst has a greater surface area compared to larger chunks of the same material, allowing for more active sites for the reaction to occur, which enhances its catalytic effectiveness.

### Step 4: Evaluate the Fourth Statement
**Statement:** The catalyst may be deactivated by heating.

**Analysis:** This statement is incorrect. Generally, heating can increase the activity of a catalyst, as it may enhance the kinetic energy of the molecules involved in the reaction. However, excessive heating can lead to catalyst deactivation in some cases, but the statement as it stands is misleading since it implies that heating generally deactivates catalysts.

### Conclusion
The incorrect statement among the options provided is the fourth statement: "The catalyst may be deactivated by heating."

---