Consider the metals in the following reactions.

2 Mg + O2 → 2 MgO
CuO + H2 → Cu + H2O
Ag+ + Cl− → AgCl

Which of the following is true?

1. Magnesium is oxidized, copper is reduced,
and silver is neither oxidized nor reduced.

2. Magnesium is oxidized; copper and silver
are reduced.

3. Magnesium is reduced; copper and silver
are neither oxidized nor reduced.

4. Magnesium and silver are oxidized; copper
is reduced.
1. Magnesium is oxidized, copper is reduced,
and silver is neither oxidized nor reduced.

The answer to your question is  the first option

Explanation:

Reactions

                            2 Mg + O₂ → 2 MgO

                            CuO + H₂ → Cu + H₂O

                            Ag+ + Cl− → AgCl

Process

1.- Determine the oxidation number of the elements

                            2 Mg⁰ + O₂⁰ → 2 Mg⁺²O

⁻²

                            Cu⁺²O⁻² + H₂⁰ → Cu⁰ + H₂⁺¹O

⁻²

                            Ag+ + Cl− → Ag⁺¹Cl⁻¹

2.- Determine if the metals were oxidized or reduced

Magnesium changed from 0 to +2                     oxidized

Copper changed from +2 to 0                            reduced

Silver changed from +1 to +1                                it did not change.