What element is being oxidized in the following redox reaction?

Zn2 + (aq) + NH4 + (aq) → Zn (s) + NO3 (aq)

The element that has been oxidized is the N

Explanation:

Zn²⁺ (aq) + NH₄⁺ (aq) → Zn (s) + NO₃⁻ (aq)

See all the oxidation states:

Zn²⁺ → acts with + 2

In ammonia, H acts with + 1 and N with - 3

Zn (s), acts with 0. In all the elements in ground state, the oxidation state is 0.

Zn changed from 2 + to 0. The oxidation number, has decreased.

This element has been reduced.

NO₃⁻ (aq) it's a ion, from nitric acid.

N acts with + 5

O acts with - 2

The global charge is - 1

The N, has increased the oxidation state, so this element is the one oxidized.