Question

Do the oxidation numbers of every element in a chemical equation have to increase/decrease for it to be considered a redox reaction?

Answer 1

No.

Explanation:

Usually, only one substance is oxidised and one substance is reduced. Most of the oxidation numbers stay the same, and the only oxidation numbers that change are for the substances that are being oxidised or reduced.

Answer 2

Nope.

Explanation:

Redox reactions are when two elements change oxidation numbers. One element gets oxidized, loses electrons, and therefore increases its oxidation number, while another element gets reduced, gains electrons, and reduces its oxidation number in the process.

Other elements/molecules that are not oxidized or reduced usually get made into new products.