Which of the following statements is typically true for a catalyst? I. The concentration of the catalyst will go down as a reaction proceeds. II. The catalyst provides a new pathway in the reaction mechanism. III. The catalyst speeds up the reaction.

II. The catalyst provides a new pathway in the reaction mechanism.

III. The catalyst speeds up the reaction.

Explanation:

Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.

A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and more molecules convert to products.

The catalyst itself does not take part in the chemical reaction and gets regenerated as such at the end of the reaction without getting consumed.

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.