Which of the following statements is true about catalysts? and why?

a. catalysts slow down the rate of chemical reactions
b. all catalysts are enzymes
c. catalysts are used up during a chemical reaction
d. catalysts lower the activation energy of a chemical reaction

answer: a chemical reaction

explanation:

im not wrong

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.