Redox Reactions MCQs for NEET — Chemistry Questions with Answers

In the reaction $ SO_2 + 2H_2S ightarrow 3S + 2H_2O $, sulphur dioxide ( $ SO_2 $ ) acts as an oxidizing agent. It oxidizes $ H_2S $ to sulfur (S), and in the process, $ SO_2 $ itself gets reduced to $ H_2O $. Hence, $ SO_2 $ is the oxidizing agent in this reaction.

When $ SO_2 $ is passed through cupric chloride ( $ CuCl_2 $ ) solution, a white precipitate of $ Cu_2Cl_2 $ is formed, and the solution becomes colorless. The reaction is: $$ SO_2 + 2CuCl_2 + 2H_2O ightarrow Cu_2Cl_2 + 2HCl + H_2SO_4 $$. Here, $ SO_2 $ reduces $ CuCl_2 $ to $ Cu_2Cl_2 $, resulting in the formation of a white precipitate and a colorless solution.

$ 3HOCl^{(+1)} \rightarrow 2HCl^{(-1)} + HCl^{(+5)}O $

$ 3HCl + HNO_3 \rightarrow NOCl + 2H_2O + Cl_2 $

$ Cl_2 + H_2O \rightarrow 2HCl + [O] $

$ 2H_2O + 2F_2 \rightarrow 4HF + O_2 $

$ HI \lt I_2 \lt ICl \lt HIO_4 $

$ K_2Cr_2O_7 + 14HCl \rightarrow 2KCl + 2 CrCl_3 + 7H_2O + 3Cl_2 $.

Reduction is a chemical reaction that involves the gain of electrons by a molecule, atom, or ion. This gain of electrons decreases the oxidation state of the substance. Therefore, the correct definition of a reduction reaction is 'a process of adding electrons.'