Which statement is true regarding a catalyst? A). A catalyst increases the activation energy for a chemical reaction.
b). A catalyst decreases the difference in energy for a chemical reaction.
c). A catalyst allows the reactants to start at a higher energy level.
d). A catalyst lowers the activation energy for a chemical reaction.

d). A catalyst lowers the activation energy for a chemical reaction.

Explanation:

From the given choices, it is true that a catalyst lowers the activation energy for a chemical reaction.

The activation energy is the energy barrier that must be overcome before a chemical reaction can occur.

Some reactions have very high activation energy and would not occur without the introduction of a catalyst.

The catalyst brings the reactants into contact by removing the energy deficiency in the system.

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.