To determine which of the given reactions is an oxidation-reduction (redox) reaction, we need to identify changes in the oxidation states of the elements involved. An oxidation-reduction reaction involves the transfer of electrons between species, resulting in changes in oxidation states.
1. Option 1:
[tex]\[
Fe_2O_3 + 3 CO \longrightarrow 2 Fe + 3 CO_2
\][/tex]
In this reaction:
- The oxidation state of Fe in \(Fe_2O_3\) is \(+3\),
- The oxidation state of Fe in the product \(2 Fe\) is \(0\).
This indicates that Fe is reduced (gain of electrons).
- The oxidation state of C in \(CO\) is \(+2\),
- The oxidation state of C in \(CO_2\) is \(+4\).
This indicates that C is oxidized (loss of electrons).
Since there are changes in the oxidation states of Fe and C, this reaction is an oxidation-reduction reaction.
2. Option 2:
[tex]\[
CuSO_4 + 2 NaOH \longrightarrow Cu(OH)_2 + Na_2SO_4
\][/tex]
In this reaction, there are no changes in the oxidation states of any of the elements involved. This is a double displacement reaction but not a redox reaction.
3. Option 3:
[tex]\[
2 NaOH + H_2CO_3 \longrightarrow Na_2CO_3 + 2 H_2O
\][/tex]
In this reaction, there are no changes in the oxidation states of any of the elements involved. This is an acid-base neutralization reaction but not a redox reaction.
4. Option 4:
[tex]\[
Pb(NO_3)_2 + Na_2SO_4 \longrightarrow 2 NaNO_3 + PbSO_4
\][/tex]
In this reaction, there are no changes in the oxidation states of any of the elements involved. This is a double displacement reaction but not a redox reaction as well.
Hence, the only oxidation-reduction reaction among the options is:
[tex]\[
Fe_2O_3 + 3 CO \longrightarrow 2 Fe + 3 CO_2
\][/tex]
Thus, the correct answer is:
[tex]\[ Fe_2O_3 + 3 CO \longrightarrow 2 Fe + 3 CO_2 \][/tex]
