Areducing chemical reaction
reduces the compound to a simpler form
adds an electron to the substrate
removes a hydrogen atom from the substrate
is a catabolic reaction

Adds an electron to the substrate.

Explanation:

A reducing chemical reaction add an electron to the substrate as, the oxidation in the chemical reaction by which there is loses in the electron of the substrate and during the reduction there is gain of electron in the substrate. So, during the loss of electron in the substrate in the oxidation process, on the other hand there is add of electron in the substrate during the reduction process.

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.