Redox Reactions Quiz - ICSE Class 11 Chemistry

Free practice quiz: Redox Reactions (ICSE Class 11 Chemistry). 50 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

This ICSE Class 11 Chemistry practice quiz has 50 multiple-choice questions on Redox Reactions, and 50 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz online. No sign-up needed.

Sample questions

1. In the reaction $2KMnO_4 + 10FeSO_4 + 8H_2SO_4 ightarrow K_2SO_4 + 2MnSO_4 + 5Fe_2(SO_4)_3 + 8H_2O$, the equivalent weight of $KMnO_4$ is:

   1. M/5
   2. M/3
   3. M/2
   4. M/1
   Show answer

   Answer: A. M/5

   In this reaction, Mn in $KMnO_4$ changes its oxidation state from +7 to +2 ($MnSO_4$). The change in oxidation state per mole of $KMnO_4$ is 5. Therefore, the number of electrons gained is 5. The equivalent weight of $KMnO_4$ is its molar mass (M) divided by the number of electrons gained, which is M/5.

2. The oxidation state of bromine in $BrF_3$ is:

   1. +1
   2. +2
   3. +3
   4. +5
   Show answer

   Answer: C. +3

   Fluorine is the most electronegative element and always has an oxidation state of -1 in its compounds, except in $F_2$. Let the oxidation state of bromine be x. In $BrF_3$, we have $x + 3(-1) = 0$. Therefore, $x = +3$.

3. The oxidation state of chromium in the chromate ion ($CrO_4^{2-}$) is:

   1. +4
   2. +5
   3. +6
   4. +7
   Show answer

   Answer: C. +6

   Let the oxidation state of chromium be x. The oxidation state of oxygen is -2. For the chromate ion ($CrO_4^{2-}$), the sum of oxidation states is equal to the charge of the ion. So, $x + 4(-2) = -2$. $x - 8 = -2$. $x = +6$.

4. In a redox reaction, the oxidizing agent is:

   1. Oxidized
   2. Reduced
   3. Neither oxidized nor reduced
   4. Both oxidized and reduced
   Show answer

   Answer: B. Reduced

   An oxidizing agent is a substance that accepts electrons from another substance, causing that other substance to be oxidized. In the process, the oxidizing agent itself gains electrons and is therefore reduced.

5. The equivalent weight of $H_3PO_3$ when it acts as an acid is:

   1. M/1
   2. M/2
   3. M/3
   4. M/4
   Show answer

   Answer: B. M/2

   Phosphorous acid ($H_3PO_3$) is a diprotic acid because one hydrogen atom is directly bonded to phosphorus and is not acidic. The acidic hydrogens are the two bonded to oxygen. The neutralization reaction is $H_3PO_3 + 2NaOH ightarrow Na_2HPO_3 + 2H_2O$. Therefore, its n-factor as an acid is 2. Equivalent weight = Molar mass (M) / n-factor = M/2.

More questions in this quiz

Answers and explanations are in the full quiz.

1. When $H_2O_2$ is passed through acidified $K_2Cr_2O_7$ solution, the color of the solution changes from:
2. Which of the following is the strongest oxidizing agent?
3. The oxidation state of sulfur in $Na_2S_4O_6$ is:
4. Which of the following species can act as both an oxidizing and reducing agent?
5. In the disproportionation reaction of chlorine in cold dilute alkali, the oxidation states of chlorine are:
6. The molar ratio of $KMnO_4$ to $H_2C_2O_4$ in the balanced redox reaction ($KMnO_4 + H_2C_2O_4 + H_2SO_4 ightarrow K_2SO_4 + MnSO_4 + CO_2 + H_2O$) is:
7. In which of the following reactions does the oxidation number of nitrogen increase?
8. The reaction between $SO_2$ and $H_2S$ in the presence of $K_2Cr_2O_7$ as a catalyst involves:
9. Consider the reaction: $2Cu(I) ightarrow Cu(0) + Cu(II)$. This is an example of:
10. Which of the following is not a redox reaction?
11. The equivalent weight of $H_3PO_4$ when it acts as an acid is:
12. In the reaction $P_4 + 3NaOH + 3H_2O ightarrow PH_3 + 3NaH_2PO_2$, the oxidation state of phosphorus changes from:
13. The oxidizing power of $O_2$, $O_3$, $F_2$ and $Cl_2$ is in the order:
14. In the reaction $2S_2O_3^{2-} + I_2 ightarrow S_4O_6^{2-} + 2I^-$, the oxidation state of sulfur changes from:
15. The standard electrode potential for $Cl_2 + 2e^- ightarrow 2Cl^-$ is +1.36 V. Which of the following can reduce $Cl_2$ to $Cl^-$?
16. In the balancing of the equation $MnO_4^- + SO_2 + H^+ ightarrow Mn^{2+} + SO_4^{2-} + H_2O$, the coefficient of $SO_2$ is:
17. Which halogen has the highest ionization energy?
18. In the reaction $H_2O_2 + O_3 ightarrow O_2 + H_2O + O_2$, what is the role of $H_2O_2$?
19. Which of the following statements is FALSE regarding redox reactions?
20. The substance which gets oxidized in the reaction $Zn + 2HCl ightarrow ZnCl_2 + H_2$ is:
21. What is the oxidation state of chlorine in $ClO_3^-$?
22. The species that cannot act as a reducing agent is:
23. The molar ratio of $Fe^{2+}$ to $MnO_4^-$ in the titration of $FeSO_4$ with $KMnO_4$ in acidic medium is:
24. Which of the following is the most powerful oxidizing agent?
25. The oxidation state of manganese in $K_2MnO_4$ is:
26. In the reaction $2CrO_4^{2-} + 2H^+ ightarrow Cr_2O_7^{2-} + H_2O$, there is:
27. Which of the following is the best reducing agent?
28. Which of the following is a disproportionation reaction?
29. In the reaction $MnO_4^{2-}$ to $MnO_2$, Mn changes oxidation state from:
30. In the reaction $P_4 + 3NaOH + 3H_2O ightarrow PH_3 + 3NaH_2PO_2$, the oxidation state of phosphorus changes from 0 to:
31. Which of the following is the strongest reducing agent?
32. Which of the following pairs of species can undergo a redox reaction?
33. The oxidation state of Iodine in $I_3^-$ is:
34. Which oxidizing agent is used in the quantitative estimation of $Fe^{2+}$ using $KMnO_4$ titration?
35. The process by which an element in a compound is simultaneously oxidized and reduced is called:
36. Which of the following is an example of a redox reaction?
37. Which of the following elements exhibits the highest electronegativity?
38. In the reaction $2S_2O_3^{2-} + I_2 ightarrow S_4O_6^{2-} + 2I^-$, the number of moles of $S_2O_3^{2-}$ that react with 1 mole of $I_2$ is:
39. Which of the following is not a characteristic of a redox reaction?
40. The oxidation state of chlorine in $HClO_4$ is:
41. Which of the following is the strongest oxidizing agent among the halogens?
42. In the reaction $2MnO_4^- + 5H_2C_2O_4 + 6H^+ ightarrow 2Mn^{2+} + 10CO_2 + 8H_2O$, the oxidation state of Mn changes from:
43. When $H_2O_2$ acts as a reducing agent, it is oxidized to:
44. The number of equivalents of $KMnO_4$ required to react completely with 1 mole of $FeSO_4$ in acidic medium is:
45. The oxidation state of sulfur in sodium thiosulfate ($Na_2S_2O_3$) is:

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