Question

select the correct answer.
in a redox reaction, why does an element’s oxidation number increase?
a. an element’s oxidation number increases because it gained electrons.
b. an element’s oxidation number increases because it lost electrons.
c. an element’s oxidation number increases because it was heated.
d. an element’s oxidation number increases because it was reduced.

Explanation:

In redox reactions, oxidation is the loss of electrons, and during oxidation, the oxidation number of an element increases. Gaining electrons (reduction) decreases the oxidation number. Heating isn't the cause of oxidation number increase, and reduction (gaining electrons) decreases, not increases, the oxidation number. So the correct reason is losing electrons.

Answer:

B. An element’s oxidation number increases because it lost electrons.