Which component is affected when a catalyst is added to a chemical reaction

A catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

Catalysts increase the rate of reaction without being used up. They do this by lowering the activation energy needed. With a catalyst, more collisions result in a reaction, so the rate of reaction increases. Different reactions need different catalysts.

Many important chemical reactions require inputs of energy to proceed. If a catalyst is present less energy will be required to complete the reaction. Catalysts are substances that are mixed in with materials that are to be reacted, but they themselves do not, in the end, change chemically.

SO, a catalyst will increase the rate of reaction of any component.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.