Given the equations A, B, C, and D:

(A) AgNO3 + NaCl → AgCl + NaNO3

(B) Cl2 + H2O → HClO + HCl

(C) CuO + CO → CO2 + Cu

(D) NaOH + HCl → NaCl + H2O

Which two equations represent redox reactions?

B and C

Explanation:

(A) AgNO₃ + NaCl → AgCl + NaNO₃

This is a double displacement reaction. It is not a redox reaction because the elements have the same oxidation numbers on both sides.

(B) Cl₂ + H₂O → HClO + HCl

This is a redox reaction.

Cl₂ is oxidized to HClO. The oxidation number of Cl increases from 0 to + 1.

Cl₂ is reduced to HCl. The oxidation number of Cl decreases from 0 to - 1.

(C) CuO + CO → CO₂ + Cu

This is a redox reaction.

CO is oxidized to CO₂. The oxidation number of C increases from + 2 to + 4.

CuO is reduced to Cu. The oxidation number of Cu decreases from + 2 to 0.

(D) NaOH + HCl → NaCl + H₂O

This is a double displacement reaction. It is not a redox reaction because the elements have the same oxidation numbers on both sides.