Question

Which of the following reactions occurs at the anode in a voltaic cell? Cu2+ (aq) + 2e– → Cu (s)

Answer 1

Mg (s) -->Mg2+2e-
i know cause i took the test and got it wrong and that's what  it showed as the right answer lol

Answer 2

Answer : The correct option is, (3) $Mg(s)\rightarrow Mg^{2+}(aq)+2e^-$

Explanation :

Voltaic cell : It is a device which is used for conversion of the chemical energy produces in a redox reaction into the electrical energy.

Voltaic cell is also known as the galvanic cell or electrochemical cell.

In the voltaic cell, the oxidation occurs at an anode which is a negative electrode and the reduction occurs at the cathode which is a positive electrode.

From the given reactions,

$Mg(s)\rightarrow Mg^{2+}(aq)+2e^-$ in this reaction, oxidation reaction takes place in which the oxidation of magnesium changes from (0) to (2+). This reaction reaction occurs at anode in voltaic cell.

While in the other reactions,

$Cu^{2+}(aq)+2e^-\rightarrow Cu(s)$ and $K^{+}(aq)+1e^-\rightarrow K(s)$ in both the reactions, the reduction reaction takes place.

And,

$Cd^{2+}+Zn\rightarrow Zn^{2+}+Cd$ this reaction shows both oxidation and reduction reaction.

Hence, the correct option is, (3) $Mg(s)\rightarrow Mg^{2+}(aq)+2e^-$