Question

Which of the following chemical reactions is an oxidation-reduction reaction? CuSO4 + BaCl2 yields BaSO4 + CuCl2 Pb(NO3)2 + 2NaCl yields PbCl2 + 2NaNO3 N2 + 3H2 yields 2NH3 K2SO4 + BaCl2 yields BaSO4 + 2KCl

Answer 1

The answer is N2 + 3H2 yields 2NH3. The oxidation-reduction reaction means that there is electrons transfer during the reaction which means that the valence changed.

Answer 2

Answer : The correct option is, $N_2+3H_2\rightarrow 2NH_3$

Explanation :

(1) $CuSO_4+BaCl_2\rightarrow BaSO_4+CuCl_2$

(2) $Pb(NO_3)_2+2NaCl\rightarrow PbCl_2+2NaNO_3$

(3) $K_2SO_4+BaCl_2\rightarrow BaSO_4+2KCl$

The reactions 1, 2, and 3 are the example of double-displacement reaction in which the cation and anion of the two reactants exchange their places to give two new compounds.

(4) $N_2+3H_2\rightarrow 2NH_3$

This reaction is an example of oxidation-reduction reaction.

Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases.

Reduction reaction : It is defined as the reaction in which a substance gains electrons. In this, oxidation state of an element decreases.

In this reaction the oxidation state of nitrogen and hydrogen is (0) and the oxidation state of nitrogen and hydrogen in $NH_3$ are, (-3) and (+1). So, from this we conclude that the nitrogen shows reduction reaction and hydrogen shows oxidation reaction.

Hence, the correct option is, $N_2+3H_2\rightarrow 2NH_3$