Question

Choose the redox reaction from the following:

• A. \( \mathrm{H_2CO_3 \rightleftharpoons H^+ + HCO_3^-} \)
• B. \( \mathrm{Hg^{2+} + 2OH^- \rightleftharpoons Hg(OH)_2} \)
• C. \( \mathrm{C_6H_{12}O_6 + 6O_2 \rightleftharpoons 6CO_2 + 6H_2O} \)
• D. \( \mathrm{CaCO_3(s) \rightleftharpoons Ca^{2+} + CO_3^{2-}} \)

Hint:

A redox reaction will always show electron transfer: something is oxidized (loses electrons), and something is reduced (gains electrons).

Answer 1

The Correct Option is C

To identify a redox reaction, we must check if there is a transfer of electrons between substances (oxidation and reduction).

Option A: \( \mathrm{H_2CO_3 \rightleftharpoons H^+ + HCO_3^-} \)
This is not a redox reaction. It is an equilibrium dissociation of carbonic acid, where no electron transfer occurs.

Option B: \( \mathrm{Hg^{2+} + 2OH^- \rightleftharpoons Hg(OH)_2} \)
This involves the precipitation of mercury (II) hydroxide but does not involve any electron transfer. Hence, it is not a redox reaction.

Option C: \( \mathrm{C_6H_{12}O_6 + 6O_2 \rightleftharpoons 6CO_2 + 6H_2O} \)
This is a classic example of a redox reaction, known as cellular respiration. In this reaction, glucose is oxidized to carbon dioxide and oxygen is reduced to water. Thus, electrons are transferred, making it a redox reaction.

Option D: \( \mathrm{CaCO_3(s) \rightleftharpoons Ca^{2+} + CO_3^{2-}} \)
This is a dissociation reaction, not a redox reaction. There is no electron transfer here.

Thus, the correct redox reaction is Option (C).