LEVEL-1
TOPIC 1: Oxidation and Reduction Reactions

1. Which quantities are conserved in all oxidation reduction reaction?

1) Charge only

2) Mass only

3) Both charges and mass

4) Neither charge nor mass

1) oxidised

2) reduced

3) precipitated

4) None of these

3. The conversion of sugar \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11} \rightarrow \mathrm{CO}_{2}\) is

1) oxidation

2) reduction

3) Both oxidation and reduction

4) Neither oxidation nor reduction

4. The product of oxidation of \(\mathrm{I}^{-}\)with \(\mathrm{MnO}_{4}^{-}\)in alkaline medium is

1) \(\mathrm{IO}^{-}\)

2) \(\mathrm{IO}_{3}^{-}\)

3) \(\mathrm{IO}_{4}^{-}\)

4) \(\mathrm{I}_{2}\)

5. In the following reaction, which is the species being oxidised ?

\(2 \mathrm{Fe}^{3+}(\mathrm{aq})+2 \mathrm{I}^{-}(\mathrm{aq}) \rightarrow \mathrm{I}_{2}(\mathrm{aq})+2 \mathrm{Fe}^{2+}(\mathrm{aq})\)

1) \(\mathrm{Fe}^{3+}\)

2) \(\mathrm{I}^{-}\)

3) \(\mathrm{I}_{2}\)

4) \(\mathrm{Fe}^{2+}\)

6. The compound that can work both as an oxidising as well as a reducing agent is

1) \(\mathrm{KMnO}_{4}\)

2) \(\mathrm{H}_{2} \mathrm{SO}_{4}\)

3) \(\mathrm{BaO}_{2}\)

4) \(\mathrm{H}_{2} \mathrm{O}_{2}\)

7. Which of the following substances acts as an oxidising as well as a reducing agent?

1) \(\mathrm{Na}_{2} \mathrm{O}\)

2) \(\mathrm{SnCl}_{2}\)

3) \(\mathrm{Na}_{2} \mathrm{O}_{2}\)

4) \(\mathrm{NaNO}_{2}\)

8. In the reaction \(2 \mathrm{FeCl}_{3}+\mathrm{H}_{2} \mathrm{~S} \rightarrow 2 \mathrm{FeCl}_{2}+2 \mathrm{HCl}+\mathrm{S}\)

1) \(\mathrm{FeCl}_{3}\) acts as an oxidising agent.

2) Both \(\mathrm{H}_{2} \mathrm{~S}\) and \(\mathrm{FeCl}_{3}\) are oxidised.

3) \(\mathrm{FeCl}_{3}\) is oxidised while \(\mathrm{H}_{2} \mathrm{~S}\) is reduced.

4) \(\mathrm{H}_{2} \mathrm{~S}\) acts as an oxidising agent.

9. When iron is rusted, it is

1) Oxidised

2) reduced

3) evaporated

4) decomposed

10. Which of the following is not an intermolecular redox reaction? 

1) \(\mathrm{MgCO}_{3} \rightarrow \mathrm{MgO}+\mathrm{CO}_{2}\)

2) \(\mathrm{O}_{2}+2 \mathrm{H}_{2} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}\)

3) \(\mathrm{K}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{KOH}+(1 / 2) \mathrm{H}_{2}\)

4) \(\mathrm{MnBr}_{3} \rightarrow \mathrm{MnBr}_{2}+(1 / 2) \mathrm{Br}_{2}\)

11. In the reaction \(3 \mathrm{Mg}+\mathrm{N}_{2} \rightarrow \mathrm{Mg}_{3} \mathrm{~N}_{2}\)

1) magnesium is reduced

2) magnesium is oxidized

3) nitrogen is oxidized

4) None of these

12. One gas bleaches the colour of flowers by reduction, while the other by oxidation

1) \(\mathrm{CO}\) and \(\mathrm{Cl}_{2}\)

2) \(\mathrm{SO}_{2}\) and \(\mathrm{Cl}_{2}\)

3) \(\mathrm{H}_{2} \mathrm{~S}\) and \(\mathrm{Br}_{2}\)

4) \(\mathrm{NH}_{3}\) and \(\mathrm{SO}_{2}\)

13. In reaction of \(\mathrm{KMnO}_{4}\) and Mohr's salt, \(\mathrm{FeSO}_{4}\) is oxidised to

1) \(\mathrm{Fe}^{2+}\)

2) \(\mathrm{Fe}^{3+}\)

3) \(\mathrm{Fe}\)

4) All of these

14. Match the columns

Column-I

Column-II

1) \(2 \mathrm{Mg}+\mathrm{O}_{2} \rightarrow 2 \mathrm{MgO}\)

(p) Removal of hydrogen

2) \(\mathrm{Mg}+\mathrm{Cl}_{2} \rightarrow \mathrm{MgCl}_{2}\)

(q) Removal of electropositive element

3) \(2 \mathrm{H}_{2} \mathrm{~S}+\mathrm{O}_{2} \rightarrow 2 \mathrm{~S}+2 \mathrm{H}_{2} \mathrm{O}\)

(r) Addition of oxygen

4) \(2 \mathrm{KI}+\mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{3} \rightarrow 2 \mathrm{KOH}+\mathrm{I}_{2}+\mathrm{O}_{2}\)

(s) Addition of electronegative element, chlorine

1) \(A-(s), B-(q), C-(p), D-(r)\)

2) \(A-(r), B-(s), C-(p), D-(q)\)

3) \(A-(s), B-(r), C-(q), D-(p)\)

4) \(A-(r), B-(p), C-(s), D-(q)\)

\section{TOPIC 2: Oxidation Number}

15. The oxidation number of chromium in potassium dichromate is

1) +6

2) -5

3) -2

4) +2

16. Phosphorus has the oxidation state of +3 in

1) phosphorous acid

2) orthophosphoric acid

3) hypophosphorous acid

4) metaphosphoric acid.

17. In which of the following reactions, nitrogen undergoes change in oxidation state?

1) \(\mathrm{NH}_{3}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{NH}_{4}^{+}+\mathrm{OH}^{-}\)

2) \(2 \mathrm{NO}_{2} \rightarrow \mathrm{N}_{2} \mathrm{O}_{4}\)

3) \(2 \mathrm{NO}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{HNO}_{3}+\mathrm{HNO}_{2}\)

d) \(\mathrm{N}_{2} \mathrm{O}_{5}+\mathrm{H}_{2} \mathrm{O} \rightarrow 2 \mathrm{HNO}_{3}\)

18. The brown ring complex compound is formulated as \(\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{5}(\mathrm{NO})\right] \mathrm{SO}_{4}\). The oxidation state of iron is

1) 1

2) 2

3) 3

4) 0

19. The pair of compounds in which both the metals are in the highest possible oxidation state is

1) \(\left[\mathrm{Fe}(\mathrm{CN})_{4}\right]^{4-},\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{3-}\)

2) \(\mathrm{CrO}_{2} \mathrm{Cl}_{2}, \mathrm{MnO}_{4}^{-}\)

3) \(\mathrm{TiO}_{3}, \mathrm{MnO}_{2}\)

4) \(\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{3-}, \mathrm{MnO}_{3}\)

20. The oxidation number of \(\mathrm{S}\) in \(\mathrm{S}_{2} \mathrm{O}_{8}^{2-}\) is

1) +2

2) +4

3) +6

4) +7

21. The oxidation number of oxygen in \(\mathrm{O}_{2} \mathrm{PtF}_{6}\) is

1) -0.5

2) Zero

3) +0.5

4) +1

22. In which of the following compounds, iron has lowest oxidation state?

1) \(\mathrm{K}_{3}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\)

2) \(\mathrm{K}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\)

3) \(\mathrm{FeSO}_{4} \cdot(\mathrm{NH} 4)_{2} \mathrm{SO}_{4} \cdot 6 \mathrm{H}_{2} \mathrm{O}\)

4) \(\mathrm{Fe}(\mathrm{CO})_{5}\)

23. In which of the compounds does 'manganese' exhibit highest oxidation number ?

1) \(\mathrm{MnO}_{2}\)

2) \(\mathrm{Mn}_{3} \mathrm{O}_{4}\)

3) \(\mathrm{K}_{2} \mathrm{MnO}_{4}\)

4) \(\mathrm{MnSO}_{4}\)

24. On reduction of \(\mathrm{KMnO}_{4}\) by oxalic acid in acidic medium, the oxidation number of Mn changes. What is the magnitude of this change?

1) From 7 to 2

2) From 6 to 2

3) From 5 to 2

4) From 7 to 4

25. When \(\mathrm{SO}_{2}\) is passed into an acidified potassium dichromate solution, the oxidation numbers of sulphur and chromium in the final products respectively are

1) \(+6,+6\)

2) \(+6,+3\)

3) \(0,+3\)

4) \(+2,+3\)

26. In which of the following coordination compounds does the transition metal have an oxidation number of +6 ? 

a) \(\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{5} \mathrm{Cl}\right] \mathrm{SO}_{4}\)

2) \(\mathrm{Cr}\left[\eta^{6}-\mathrm{C}_{6} \mathrm{H}_{6}\right]_{2}\)

c) \(\mathrm{K}_{2}\left[\mathrm{Cr}(\mathrm{CN})_{2} \mathrm{O}_{2}\left(\mathrm{O}_{2}\right) \mathrm{NH}_{3}\right]\)

d) \(\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{4}(\mathrm{SCN})_{2}\right]\left[\mathrm{CR}\left(\mathrm{NH}_{3}\right)_{2}(\mathrm{SCN})_{4}\right]\)

27. In which of the following transition metal complexes does the metal exhibit zero oxidation state ?

1) \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right] \mathrm{Cl}_{3}\)

2) \(\left.\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right] \mathrm{SO}_{4} 3\right) \mathrm{Ni}(\mathrm{CO})_{4}\)

4) \(\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right] \mathrm{X}_{3}\)

28. Oxidation numbers of chlorine atoms in \(\mathrm{CaOCl}_{2}\) are

1) 0,0

2) \(-1,-1\)

3) \(-1,+1\)

4) None of these

29. The oxide, which cannot act as a reducing agent, is

1) \(\mathrm{NO}_{2}\)

2) \(\mathrm{SO}_{2}\)

3) \(\mathrm{CO}_{2}\)

4) \(\mathrm{ClO}_{2}\)

30. Point out the correct statement of the following about \(\mathrm{Na}_{2} \mathrm{~S}_{4} \mathrm{O}_{6}\).

1) Average oxidation number of \(S\) atom is +2

2) Oxidation number of two \(S\) atoms is zero each and that of other two is +5 each

3) Oxidation number of two \(S\) atoms is +1 each and that of other two is +4 each

4) None of these

31. The oxidation state of the most electronegative element in the products of the reaction between \(\mathrm{BaO}_{2}\) and \(\mathrm{H}_{2} \mathrm{SO}_{4}\) are

1) 0 and -1

2) -1 and -2

3) -2 and 0

4) -2 and +1

32. When ethane is burnt in presence of excess of oxygen, the oxidation number of carbon changes by

1) +8

2) +7

3) +3

4) +4

\section{TOPIC 3: Disproportionation and Balancing of Redox Reactions}

33. Which of the following is not a redox reaction?

1) \(4 \mathrm{KClO}_{3} \rightarrow 3 \mathrm{KClO}_{4}+\mathrm{KCl}\)

2) \(\mathrm{Na}_{2} \mathrm{O}+2 \mathrm{HCl} \rightarrow 2 \mathrm{NaCl}+\mathrm{H}_{2} \mathrm{O}\)

3) \(\mathrm{SO}_{2}+2 \mathrm{H}_{2} \mathrm{~S} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}+3 \mathrm{~S}\)

4) \(2 \mathrm{Na}+\mathrm{O}_{2} \rightarrow \mathrm{Na}_{2} \mathrm{O}_{2}\)

34. For the reaction : \(\mathrm{NH}_{3}+\mathrm{OCl}^{-} \rightarrow \mathrm{N}_{2} \mathrm{H}_{4}+\mathrm{Cl}^{-}\)in basic medium, the coefficients of \(\mathrm{NH}_{3}, \mathrm{OCl}^{-}\)and \(\mathrm{N}_{2} \mathrm{H}_{4}\) for the balanced equation are respectively.

1) 2, 2, 2

2) 2, 2, 1

3) \(2,1,1\)

4) 4, 4, 2

35. In the reaction, \(\mathrm{Cl}_{2}+2 \mathrm{OH}^{-} \rightarrow \mathrm{OCl}^{-}+\mathrm{Cl}^{-}+\mathrm{H}_{2} \mathrm{O}\)

1) \(\mathrm{OH}^{-}\)is oxidising and \(\mathrm{Cl}_{2}\) is reducing agent 2) \(\mathrm{Cl}_{2}\) is oxidising and \(\mathrm{OH}^{-}\)is reducing agent

3) \(\mathrm{OH}^{-}\)is both oxidising and reducing agent 4) \(\mathrm{Cl}_{2}\) is both oxidising and reducing agent

36. When phosphorous reacts with caustic soda, the products are \(\mathrm{PH}_{3}\) and \(\mathrm{NaH}_{2} \mathrm{PO}_{2}\). This reaction is an example of

1) oxidation

2) reduction

3) disproportionation

4) none of these

37. \(\mathrm{KMnO}_{4}\) oxidises oxalic acid in acidic medium. The number of \(\mathrm{CO}_{2}\) molecules produced as per the balanced equation is

1) 10

2) 8

3) 6

4) 3

38. Which of the following does not represent redox reaction?

1) \(2 \mathrm{Ca}(\mathrm{OH})_{2}+\mathrm{Cl}_{2} \rightarrow \mathrm{Ca}(\mathrm{ClO})_{2}+\mathrm{CaCl}_{2}+2 \mathrm{H}_{2} \mathrm{O}\)

2) \(\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+2 \mathrm{OH}^{-} \rightarrow 2 \mathrm{CrO}_{4}^{2-}+\mathrm{H}_{2} \mathrm{O}\)

3) \(\mathrm{NaIO}_{3}+\mathrm{NaHSO}_{3} \rightarrow \mathrm{NaHSO}_{4}+\mathrm{Na}_{2} \mathrm{SO}_{4}+\mathrm{I}_{2}+\mathrm{H}_{2} \mathrm{O}\) 4) \(2 \mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}+\mathrm{I}_{2} \rightarrow \mathrm{Na}_{2} \mathrm{~S}_{4} \mathrm{O}_{6}+2 \mathrm{NaI}\)

39. Amongst the following, the strongest oxidising agent is

1) \(\mathrm{KMnO}_{4}\)

2) \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\)

3) \(\mathrm{H}_{2} \mathrm{O}_{2}\)

4) \(\mathrm{O}_{3}\)

40. Number of moles of \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) reduced by one mole of \(\mathrm{Sn}^{2+}\) ions is

1) \(1 / 3\)

2) 3

3) \(1 / 6\)

4) 6

41. The reaction \(3 \mathrm{ClO}^{-}(\mathrm{aq}) \rightarrow \mathrm{ClO}_{3}^{-}(\mathrm{aq})+2 \mathrm{Cl}^{-}(\mathrm{aq})\) is an example of -

1) Oxidation reaction

2) Reduction reaction

3) Disproportionation reaction

4) Decomposition reaction

42. The species that undergoes disproportionation in an alkaline medium are

1) \(\mathrm{Cl}_{2}\)

2) \(\mathrm{MnO}_{4}^{2-}\)

3) \(\mathrm{NO}_{2}\)

4) All of these 43. What products are expected from the disproportionation reaction of hypochlorous acid?

1) \(\mathrm{HCl}\) and \(\mathrm{Cl}_{2} \mathrm{O}\)

2) \(\mathrm{HCl}\) and \(\mathrm{HClO}_{3}\)

3) \(\mathrm{HClO}_{3}\) and \(\mathrm{Cl}_{2} \mathrm{O}\)

4) \(\mathrm{HClO}_{2}\) and \(\mathrm{HClO}_{4}\)

44. Amongst the following which can act as an oxidising as well as reducing agent?

1) \(\mathrm{F}_{2}\)

2) \(\mathrm{SO}_{3}\)

3) \(\mathrm{H}_{2} \mathrm{O}_{2}\)

4) \(\mathrm{H}_{2} \mathrm{O}\)

45. The number of electrons lost in the following change is \(\mathrm{Fe}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{Fe}_{3} \mathrm{O}_{4}+\mathrm{H}_{2}\)

1) 2

2) 4

3) 6

4) 8

46. In which of the following reactions, \(\mathrm{SO}_{2}\) behaves as an oxidising agent?

1) \(2 \mathrm{MnO}_{4}^{-}+5 \mathrm{SO}_{2}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow 5 \mathrm{SO}_{4}^{2-}+2 \mathrm{Mn}^{2+}+4 \mathrm{H}^{+}\)

2) \(\mathrm{Cl}_{2}+\mathrm{SO}_{2} \rightarrow \mathrm{SO}_{2} \mathrm{Cl}_{2}\)

3) \(2 \mathrm{H}_{2} \mathrm{~S}+\mathrm{SO}_{2} \rightarrow 3 \mathrm{~S}+2 \mathrm{H}_{2} \mathrm{O}\)

4) \(\mathrm{SO}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{H}_{2} \mathrm{SO}_{3}\)

47. The oxidation numbers of \(\mathrm{C}-1, \mathrm{C}-2\) and \(\mathrm{C}-3\) in propyne \(\left(\stackrel{3}{\mathrm{C}} \mathrm{H}_{3} \stackrel{2}{\mathrm{C}} \equiv \stackrel{1}{\mathrm{C}} \mathrm{H}\right)\) respectively are

1) \(-1,0,-3\)

2) \(-1,1,-4\)

3) \(-2,0,-3\)

4) \(+1,-2,-3\)

\section{TOPIC 4: Electrode Potential}

48. Standard reduction potentials of the half reactions are given below :

\[

\begin{aligned}

& \mathrm{F}_{2}(\mathrm{~g})+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{~F}^{-}(\mathrm{aq}) ; \mathrm{E}^{\circ}=+2.85 \mathrm{~V} \\

& \mathrm{Cl}_{2}(\mathrm{~g})+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cl}^{-} \text {(aq); } \mathrm{E}^{\circ}=+1.36 \mathrm{~V} \\

& \mathrm{Br}_{2}(\mathrm{l})+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{Br}^{-}(\mathrm{aq}) ; \mathrm{E}^{\circ}=+1.06 \mathrm{~V} \\

& \mathrm{I}_{2}(\mathrm{~s})+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{I}^{-} \text {(aq) } ; \mathrm{E}^{\circ}=+0.53 \mathrm{~V}

\end{aligned}

\]

The strongest oxidising and reducing agents respectively are :

1) \(\mathrm{F}_{2}\) and \(\mathrm{I}^{-}\)

2) \(\mathrm{Br}_{2}\) and \(\mathrm{Cl}^{-}\)

3) \(\mathrm{Cl}_{2}\) and \(\mathrm{Br}^{-}\)

4) \(\mathrm{Cl}_{2}\) and \(\mathrm{I}_{2}\)

49. Standard electrode potentials of redox couples

\(\mathrm{A}^{2+} / \mathrm{A}, \mathrm{B}^{2+} / \mathrm{B}, \mathrm{C} / \mathrm{C}^{2+}\) and \(\mathrm{D}^{2+} / \mathrm{D}\) are \(0.3 \mathrm{~V},-0.5 \mathrm{~V},-0.75 \mathrm{~V}\) and \(0.9 \mathrm{~V}\) respectively. Which of these is best oxidising agent and reducing agent respectively -

1) \(\mathrm{D}^{2+} / \mathrm{D}\) and \(\mathrm{B}^{2+} / \mathrm{B}\)

2) \(\mathrm{B}^{2+} / \mathrm{B}\) and \(\mathrm{D}^{2+} / \mathrm{D}\)

3) \(\mathrm{D}^{2+} / \mathrm{D}\) and \(\mathrm{C}^{2+} / \mathrm{C}\)

4) \(\mathrm{C}^{2+} / \mathrm{C}\) and \(\mathrm{D}^{2+} / \mathrm{D}\)

50. The standard electrode potentials of four elements A, B, C and D are \(-3.05,-1.66,-0.40\) and +0.80 . The highest chemical reactivity will be exhibited by :

1) \(A\)

2) B

3) \(C\)

4) \(\mathrm{D}\)