What is not true for a catalyst? 1. a catalyst increases the rate of a chemical reaction by decreasing activation energy. 2. a catalyst is not consumed in chemical reactions. 3. a catalyst can convert an endothermic reaction into an exothermic reaction. 4. a catalyst may be used in the solid, liquid or gaseous phase.

3. A catalyst can convert an endothermic reaction into an exothermic reaction.

Explanation:

What is NOT true for a catalyst?

1. A catalyst increases the rate of a chemical reaction by decreasing activation energy. TRUE. A positive catalyst increases the reaction rate by decreasing the activation energy.

2. A catalyst is not consumed in chemical reactions. TRUE. A catalyst is recovered unaltered at the end of the reaction.

3. A catalyst can convert an endothermic reaction into an exothermic reaction. FALSE. A catalyst cannot modify the enthalpy of a reaction.

4. A catalyst may be used in the solid, liquid or gaseous phase. TRUE. If the catalyst is in the same phase as the reaction, the catalysis is homogeneous. Else, the catalysis is heterogeneous.