{"id":15375,"date":"2025-11-05T05:56:39","date_gmt":"2025-11-05T05:56:39","guid":{"rendered":"https:\/\/mcqsadda.com\/?p=15375"},"modified":"2025-11-05T06:13:35","modified_gmt":"2025-11-05T06:13:35","slug":"oxidation-and-reduction-top-100-mcqs-with-answer-and-explanation-2","status":"publish","type":"post","link":"https:\/\/mcqsadda.com\/index.php\/2025\/11\/05\/oxidation-and-reduction-top-100-mcqs-with-answer-and-explanation-2\/","title":{"rendered":"Oxidation and reduction Top 100 MCQs With Answer and Explanation"},"content":{"rendered":"\n

1. Oxidation involves:<\/mark>
<\/strong>A) Gain of electrons
B) Loss of electrons
C) Gain of protons
D) None of these
Answer:<\/strong> B
Explanation:<\/strong> Oxidation is the process of loss of electrons<\/strong> from an atom or ion.<\/p>\n\n\n\n

2. Reduction involves:<\/mark>
<\/strong>A) Loss of electrons
B) Gain of electrons
C) Gain of oxygen
D) None of these
Answer:<\/strong> B
Explanation:<\/strong> Reduction is the gain of electrons<\/strong> by an atom, ion, or molecule.<\/p>\n\n\n\n

3. Which of the following represents oxidation?<\/mark>
<\/strong>A) Fe \u2192 Fe\u00b2\u207a + 2e\u207b
B) Cl\u2082 + 2e\u207b \u2192 2Cl\u207b
C) Cu\u00b2\u207a + 2e\u207b \u2192 Cu
D) H\u2082 + Cl\u2082 \u2192 2HCl
Answer:<\/strong> A
Explanation:<\/strong> Iron loses two electrons\u2014thus it is oxidized.<\/p>\n\n\n\n

4. Which of the following represents reduction?<\/mark>
<\/strong>A) Zn \u2192 Zn\u00b2\u207a + 2e\u207b
B) Cu\u00b2\u207a + 2e\u207b \u2192 Cu
C) Fe \u2192 Fe\u00b3\u207a + 3e\u207b
D) O\u2082 \u2192 2O
Answer:<\/strong> B
Explanation:<\/strong> Copper ion gains electrons and gets reduced.<\/p>\n\n\n\n

5. In a redox reaction, the oxidizing agent:<\/mark>
<\/strong>A) Gets oxidized
B) Gets reduced
C) Loses electrons
D) Remains unchanged
Answer:<\/strong> B
Explanation:<\/strong> The oxidizing agent causes oxidation<\/strong> of another substance and itself gets reduced<\/strong>.<\/p>\n\n\n\n

6. The reducing agent:<\/mark><\/strong>
A) Causes reduction
B) Is reduced itself
C) Gains electrons
D) Is oxidized itself
Answer:<\/strong> D
Explanation:<\/strong> The reducing agent donates electrons<\/strong>, gets oxidized<\/strong>, and causes reduction.<\/p>\n\n\n\n

7. Which of the following is both oxidized and reduced in the same reaction?<\/mark><\/strong>
A) H\u2082O\u2082
B) O\u2082
C) H\u2082
D) Cl\u2082
Answer:<\/strong> A
Explanation:<\/strong> In its decomposition, H\u2082O\u2082 acts as both oxidizing and reducing agent.<\/p>\n\n\n\n

8. In the reaction<\/mark><\/strong>
Zn + CuSO\u2084 \u2192 ZnSO\u2084 + Cu,
which is the oxidizing agent?
A) Zn
B) Cu\u00b2\u207a
C) SO\u2084\u00b2\u207b
D) Cu
Answer:<\/strong> B
Explanation:<\/strong> Cu\u00b2\u207a accepts electrons (is reduced), so it is the oxidizing agent.<\/p>\n\n\n\n

9. In the same reaction, the reducing agent is:<\/mark><\/strong>
A) Zn
B) Cu\u00b2\u207a
C) Cu
D) SO\u2084\u00b2\u207b
Answer:<\/strong> A
Explanation:<\/strong> Zn loses electrons and is oxidized\u2014hence the reducing agent.<\/p>\n\n\n\n

10. Oxidation number of oxygen in H\u2082O\u2082 is:<\/mark><\/strong>
A) -2
B) -1
C) 0
D) +1
Answer:<\/strong> B
Explanation:<\/strong> Each oxygen in H\u2082O\u2082 has oxidation state -1<\/strong>.<\/p>\n\n\n\n

11. The oxidation number of sulfur in H\u2082SO\u2084 is:<\/mark><\/strong>
A) +4
B) +6
C) +2
D) +3
Answer:<\/strong> B
Explanation:<\/strong> 2(+1)+x+4(\u22122)=0\u21d2x=+62(+1) + x + 4(-2) = 0 \\Rightarrow x = +62(+1)+x+4(\u22122)=0\u21d2x=+6<\/p>\n\n\n\n

12. Which of the following has zero oxidation number?<\/mark><\/strong>
A) H\u2082
B) NaCl
C) H\u2082O
D) NaOH
Answer:<\/strong> A
Explanation:<\/strong> Free elements have zero oxidation number.<\/p>\n\n\n\n

13. Which is not an oxidizing agent?<\/mark><\/strong>
A) KMnO\u2084
B) K\u2082Cr\u2082O\u2087
C) Na\u2082S
D) H\u2082O\u2082
Answer:<\/strong> C
Explanation:<\/strong> Na\u2082S acts as a reducing agent.<\/p>\n\n\n\n

14. The oxidation state of nitrogen in NH\u2083 is:<\/mark><\/strong>
A) +3
B) -3
C) 0
D) +5
Answer:<\/strong> B
Explanation:<\/strong> x+3(+1)=0\u21d2x=\u22123x + 3(+1) = 0 \\Rightarrow x = -3x+3(+1)=0\u21d2x=\u22123<\/p>\n\n\n\n

15. Which element undergoes oxidation in the reaction<\/mark><\/strong>
2Mg + O\u2082 \u2192 2MgO?
A) O
B) Mg
C) Both
D) None
Answer:<\/strong> B
Explanation:<\/strong> Mg loses electrons and is oxidized.<\/p>\n\n\n\n

16. Which undergoes reduction in above reaction?<\/mark><\/strong>
A) O\u2082
B) Mg
C) Both
D) None
Answer:<\/strong> A
Explanation:<\/strong> O\u2082 gains electrons forming oxide ion.<\/p>\n\n\n\n

17. The oxidation number of chlorine in NaClO\u2083 is:<\/mark><\/strong>
A) +1
B) +3
C) +5
D) +7
Answer:<\/strong> C
Explanation:<\/strong> +1+x+3(\u22122)=0\u21d2x=+5+1 + x + 3(-2) = 0 \\Rightarrow x = +5+1+x+3(\u22122)=0\u21d2x=+5<\/p>\n\n\n\n

18. Disproportionation reaction means:<\/mark><\/strong>
A) Oxidation and reduction of same element
B) Only oxidation occurs
C) Only reduction occurs
D) None
Answer:<\/strong> A
Explanation:<\/strong> In disproportionation, the same element<\/strong> is both oxidized and reduced.<\/p>\n\n\n\n

19. Example of disproportionation reaction is:<\/mark><\/strong>
A) 2H\u2082O\u2082 \u2192 2H\u2082O + O\u2082
B) Zn + CuSO\u2084 \u2192 ZnSO\u2084 + Cu
C) 2Mg + O\u2082 \u2192 2MgO
D) H\u2082 + Cl\u2082 \u2192 2HCl
Answer:<\/strong> A
Explanation:<\/strong> Oxygen in H\u2082O\u2082 changes from -1 to 0 and -2.<\/p>\n\n\n\n

20. Oxidation number of Mn in KMnO\u2084 is:<\/mark><\/strong>
A) +4
B) +6
C) +7
D) +2
Answer:<\/strong> C
Explanation:<\/strong> +1+x+4(\u22122)=0\u21d2x=+7+1 + x + 4(-2) = 0 \\Rightarrow x = +7+1+x+4(\u22122)=0\u21d2x=+7<\/p>\n\n\n\n

21. Oxidation number of Cr in K\u2082Cr\u2082O\u2087 is:<\/mark><\/strong>
A) +3
B) +6
C) +2
D) +7
Answer:<\/strong> B
Explanation:<\/strong> 2(+1)+2x+7(\u22122)=0\u21d2x=+62(+1) + 2x + 7(-2) = 0 \\Rightarrow x = +62(+1)+2x+7(\u22122)=0\u21d2x=+6

22. Oxidation number of Fe in Fe\u2082O\u2083 is:<\/mark><\/strong>
A) +2
B) +3
C) +1
D) +6
Answer:<\/strong> B
Explanation:<\/strong> 2x+3(\u22122)=0\u21d2x=+32x + 3(-2) = 0 \\Rightarrow x = +32x+3(\u22122)=0\u21d2x=+3<\/p>\n\n\n\n

23. Which of the following is a reducing agent?<\/mark><\/strong>
A) H\u2082
B) O\u2082
C) Cl\u2082
D) KMnO\u2084
Answer:<\/strong> A
Explanation:<\/strong> H\u2082 donates electrons and hence acts as a reducing agent.<\/p>\n\n\n\n

24. Which is an oxidizing agent?<\/mark><\/strong>
A) CO
B) H\u2082S
C) O\u2083
D) SO\u2082
Answer:<\/strong> C
Explanation:<\/strong> Ozone (O\u2083) readily releases oxygen and acts as a strong oxidizing agent.

25. The oxidation number of N in HNO\u2083 is:<\/mark><\/strong>
A) +3
B) +5
C) +2
D) +4
Answer:<\/strong> B
Explanation:<\/strong> +1+x+3(\u22122)=0\u21d2x=+5+1 + x + 3(-2) = 0 \\Rightarrow x = +5+1+x+3(\u22122)=0\u21d2x=+5<\/p>\n\n\n\n

26. In Fe + CuSO\u2084 \u2192 FeSO\u2084 + Cu, Fe is:<\/mark><\/strong>
A) Oxidized
B) Reduced
C) Unchanged
D) Catalyst
Answer:<\/strong> A
Explanation:<\/strong> Fe \u2192 Fe\u00b2\u207a + 2e\u207b (oxidation).<\/p>\n\n\n\n

27. The oxidation number of S in SO\u2082 is:<\/mark><\/strong>
A) +2
B) +4
C) +6
D) 0
Answer:<\/strong> B
Explanation:<\/strong> x+2(\u22122)=0\u21d2x=+4x + 2(-2) = 0 \\Rightarrow x = +4x+2(\u22122)=0\u21d2x=+4<\/p>\n\n\n\n

28. Which of the following involves reduction?<\/mark><\/strong>
A) Addition of oxygen
B) Addition of hydrogen
C) Loss of hydrogen
D) None
Answer:<\/strong> B
Explanation:<\/strong> Reduction can also be defined as gain of hydrogen.<\/p>\n\n\n\n

29. Which of the following is a redox reaction?<\/mark><\/strong>
A) NaCl + AgNO\u2083 \u2192 AgCl + NaNO\u2083
B) 2Mg + O\u2082 \u2192 2MgO
C) BaCl\u2082 + H\u2082SO\u2084 \u2192 BaSO\u2084 + 2HCl
D) NaOH + HCl \u2192 NaCl + H\u2082O
Answer:<\/strong> B
Explanation:<\/strong> There is transfer of electrons \u2014 oxidation of Mg and reduction of O\u2082.<\/p>\n\n\n\n

30. Oxidation number of Cl in HClO\u2084 is:<\/mark><\/strong>
A) +1
B) +3
C) +5
D) +7
Answer:<\/strong> D
Explanation:<\/strong> +1+x+4(\u22122)=0\u21d2x=+7+1 + x + 4(-2) = 0 \\Rightarrow x = +7+1+x+4(\u22122)=0\u21d2x=+7<\/p>\n\n\n\n

31. Oxidation number of Mn in MnO\u2082 is:<\/mark><\/strong>
A) +2
B) +4
C) +6
D) +7
Answer:<\/strong> B
Explanation:<\/strong> x+2(\u22122)=0\u21d2x=+4x + 2(-2) = 0 \\Rightarrow x = +4x+2(\u22122)=0\u21d2x=+4<\/p>\n\n\n\n

32. Which of the following is a disproportionation reaction?<\/mark><\/strong>
A) 3Cl\u2082 + 6NaOH \u2192 5NaCl + NaClO\u2083 + 3H\u2082O
B) Zn + CuSO\u2084 \u2192 ZnSO\u2084 + Cu
C) Mg + O\u2082 \u2192 MgO
D) H\u2082 + Cl\u2082 \u2192 2HCl
Answer:<\/strong> A
Explanation:<\/strong> Chlorine undergoes both oxidation and reduction.<\/p>\n\n\n\n

33. In the reaction<\/mark><\/strong>
Cl\u2082 + 2KI \u2192 2KCl + I\u2082,
oxidizing agent is:
A) KI
B) Cl\u2082
C) K\u207a
D) I\u2082
Answer:<\/strong> B
Explanation:<\/strong> Cl\u2082 gains electrons and oxidizes iodide ions.<\/p>\n\n\n\n

34. In the same reaction, reducing agent is:<\/mark><\/strong>
A) KI
B) Cl\u2082
C) K\u207a
D) I\u2082
Answer:<\/strong> A
Explanation:<\/strong> I\u207b loses electrons and is oxidized.<\/p>\n\n\n\n

35. Oxidation number of oxygen in OF\u2082 is:<\/mark><\/strong>
A) -2
B) -1
C) 0
D) +2
Answer:<\/strong> D
Explanation:<\/strong> x+2(\u22121)=0\u21d2x=+2x + 2(-1) = 0 \\Rightarrow x = +2x+2(\u22121)=0\u21d2x=+2<\/p>\n\n\n\n

36. In the reaction<\/mark><\/strong>
Zn + 2HCl \u2192 ZnCl\u2082 + H\u2082,
hydrogen is:
A) Oxidized
B) Reduced
C) Unchanged
D) Catalyst
Answer:<\/strong> B
Explanation:<\/strong> H\u207a gains electrons \u2192 H\u2082 (reduction).<\/p>\n\n\n\n

37. The oxidation number of carbon in CO\u2082 is:<\/mark><\/strong>
A) +4
B) +2
C) 0
D) -4
Answer:<\/strong> A
Explanation:<\/strong> x+2(\u22122)=0\u21d2x=+4x + 2(-2) = 0 \\Rightarrow x = +4x+2(\u22122)=0\u21d2x=+4

38. The oxidation number of C in CH\u2084 is:<\/strong><\/mark>
A) -4
B) +4
C) -2
D) +2
Answer:<\/strong> A
Explanation:<\/strong> x+4(+1)=0\u21d2x=\u22124x + 4(+1) = 0 \\Rightarrow x = -4x+4(+1)=0\u21d2x=\u22124<\/p>\n\n\n\n

39. In the reaction<\/mark><\/strong>
2H\u2082 + O\u2082 \u2192 2H\u2082O,
oxidizing agent is:
A) H\u2082
B) O\u2082
C) H\u2082O
D) None
Answer:<\/strong> B
Explanation:<\/strong> O\u2082 gains electrons (reduced), thus oxidizing agent.<\/p>\n\n\n\n

40. Reducing agent in the same reaction is:<\/mark><\/strong>
A) H\u2082
B) O\u2082
C) H\u2082O
D) None
Answer:<\/strong> A
Explanation:<\/strong> H\u2082 is oxidized, hence reducing agent.<\/p>\n\n\n\n

41. The oxidation number of nitrogen in N\u2082O is:<\/mark><\/strong>
A) +1
B) +2
C) +3
D) +4
Answer:<\/strong> A
Explanation:<\/strong> 2x+(\u22122)=0\u21d2x=+12x + (-2) = 0 \\Rightarrow x = +12x+(\u22122)=0\u21d2x=+1<\/p>\n\n\n\n

42. Oxidation number of N in NH\u2084\u207a is:<\/mark><\/strong>
A) -3
B) +3
C) -4
D) -2
Answer:<\/strong> A
Explanation:<\/strong> x+4(+1)=+1\u21d2x=\u22123x + 4(+1) = +1 \\Rightarrow x = -3x+4(+1)=+1\u21d2x=\u22123<\/p>\n\n\n\n

43. Oxidation number of Cl in NaOCl is:<\/mark><\/strong>
A) +1
B) -1
C) +3
D) +5
Answer:<\/strong> A
Explanation:<\/strong> +1+x+(\u22122)=0\u21d2x=+1+1 + x + (-2) = 0 \\Rightarrow x = +1+1+x+(\u22122)=0\u21d2x=+1<\/p>\n\n\n\n

44. Oxidation number of P in H\u2083PO\u2084 is:<\/mark><\/strong>
A) +3
B) +5
C) +4
D) +2
Answer:<\/strong> B
Explanation:<\/strong> 3(+1)+x+4(\u22122)=0\u21d2x=+53(+1) + x + 4(-2) = 0 \\Rightarrow x = +53(+1)+x+4(\u22122)=0\u21d2x=+5<\/p>\n\n\n\n

45. Which is the oxidizing agent in the reaction<\/mark><\/strong>
Cu + 2AgNO\u2083 \u2192 Cu(NO\u2083)\u2082 + 2Ag?
A) Cu
B) Ag\u207a
C) NO\u2083\u207b
D) Ag
Answer:<\/strong> B
Explanation:<\/strong> Ag\u207a gains electrons (reduced).<\/p>\n\n\n\n

46. Reducing agent in the above reaction is:<\/mark><\/strong>
A) Cu
B) Ag\u207a
C) NO\u2083\u207b
D) Ag
Answer:<\/strong> A
Explanation:<\/strong> Cu is oxidized to Cu\u00b2\u207a, acts as reducing agent.<\/p>\n\n\n\n

47. Oxidation number of S in H\u2082S is:<\/mark><\/strong>
A) -2
B) +2
C) 0
D) +4
Answer:<\/strong> A
Explanation:<\/strong> 2(+1)+x=0\u21d2x=\u221222(+1) + x = 0 \\Rightarrow x = -22(+1)+x=0\u21d2x=\u22122<\/p>\n\n\n\n

48. Which of the following is an example of oxidation?<\/mark><\/strong>
A) Addition of oxygen
B) Addition of hydrogen
C) Gain of electrons
D) None
Answer:<\/strong> A
Explanation:<\/strong> Oxidation also means addition of oxygen.<\/p>\n\n\n\n

49. Which species is oxidized in reaction:<\/mark><\/strong>
Zn + H\u2082SO\u2084 \u2192 ZnSO\u2084 + H\u2082 ?
A) Zn
B) H\u2082
C) H\u207a
D) SO\u2084\u00b2\u207b
Answer:<\/strong> A
Explanation:<\/strong> Zn \u2192 Zn\u00b2\u207a (oxidation).<\/p>\n\n\n\n

50. Oxidation number of Fe in Fe\u2083O\u2084 is:<\/mark><\/strong>
A) +2
B) +3
C) Average +2.67
D) +1
Answer:<\/strong> C
Explanation:<\/strong> Fe\u2083O\u2084 = FeO\u00b7Fe\u2082O\u2083 \u2192 average = (2 + 2\u00d73)\/3 = +2.67<\/p>\n\n\n\n

51. Redox reaction involves:<\/mark><\/strong>
A) Transfer of protons
B) Transfer of electrons
C) Transfer of ions
D) None
Answer:<\/strong> B
Explanation:<\/strong> Redox reaction is based on electron transfer.<\/p>\n\n\n\n

52. Oxidation number of S in Na\u2082SO\u2084 is:<\/mark><\/strong>
A) +4
B) +6
C) +2
D) +3
Answer:<\/strong> B
Explanation:<\/strong> 2(+1)+x+4(\u22122)=0\u21d2x=+62(+1) + x + 4(-2) = 0 \\Rightarrow x = +62(+1)+x+4(\u22122)=0\u21d2x=+6<\/p>\n\n\n\n

53. Oxidation number of Cl in ClO\u2082 is:<\/mark><\/strong>
A) +1
B) +3
C) +4
D) +5
Answer:<\/strong> C
Explanation:<\/strong> x+2(\u22122)=0\u21d2x=+4x + 2(-2) = 0 \\Rightarrow x = +4x+2(\u22122)=0\u21d2x=+4<\/p>\n\n\n\n

54. The oxidation number of oxygen in O\u2082F\u2082 is:<\/mark><\/strong>
A) -1
B) 0
C) +1
D) +2
Answer:<\/strong> C
Explanation:<\/strong> 2x+2(\u22121)=0\u21d2x=+12x + 2(-1) = 0 \\Rightarrow x = +12x+2(\u22121)=0\u21d2x=+1<\/p>\n\n\n\n

55. Oxidation number of S in SO\u2083\u00b2\u207b is:<\/mark><\/strong>
A) +4
B) +6
C) +2
D) 0
Answer:<\/strong> A
Explanation:<\/strong> x+3(\u22122)=\u22122\u21d2x=+4x + 3(-2) = -2 \\Rightarrow x = +4x+3(\u22122)=\u22122\u21d2x=+4<\/p>\n\n\n\n

56. The oxidizing agent is always the species that:<\/mark><\/strong>
A) Loses electrons
B) Gains electrons
C) Gets oxidized
D) Donates protons
Answer:<\/strong> B
Explanation:<\/strong> Oxidizing agent gains electrons \u2192 gets reduced.<\/p>\n\n\n\n

57. Reducing agent always:<\/mark><\/strong>
A) Accepts electrons
B) Donates electrons
C) Gains oxygen
D) Gains protons
Answer:<\/strong> B
Explanation:<\/strong> Reducing agent donates electrons \u2192 gets oxidized.<\/p>\n\n\n\n

58. In acidic medium, MnO\u2084\u207b reduces to:<\/mark><\/strong>
A) Mn\u00b2\u207a
B) MnO\u2082
C) Mn\u00b3\u207a
D) Mn\u2074\u207a
Answer:<\/strong> A
Explanation:<\/strong> Mn\u2077\u207a in permanganate is reduced to Mn\u00b2\u207a in acidic medium.<\/p>\n\n\n\n

59. In neutral medium, MnO\u2084\u207b reduces to:<\/mark><\/strong>
A) Mn\u00b2\u207a
B) MnO\u2082
C) Mn\u00b3\u207a
D) MnO\u2084\u00b2\u207b
Answer:<\/strong> B
Explanation:<\/strong> In neutral medium, MnO\u2084\u207b \u2192 MnO\u2082.<\/p>\n\n\n\n

60. In basic medium, MnO\u2084\u207b reduces to:<\/mark><\/strong>
A) MnO\u2084\u00b2\u207b
B) Mn\u00b2\u207a
C) MnO\u2082
D) Mn\u00b3\u207a
Answer:<\/strong> A
Explanation:<\/strong> Mn\u2077\u207a \u2192 Mn\u2076\u207a in basic medium (MnO\u2084\u00b2\u207b).<\/p>\n\n\n\n

61. Oxidation number of N in NO\u2082\u207b is:<\/mark><\/strong>
A) +2
B) +3
C) +4
D) +5
Answer:<\/strong> B
Explanation:<\/strong> x+2(\u22122)=\u22121\u21d2x=+3x + 2(-2) = -1 \\Rightarrow x = +3x+2(\u22122)=\u22121\u21d2x=+3<\/p>\n\n\n\n

62. Oxidation number of N in NO\u2083\u207b is:<\/mark><\/strong>
A) +2
B) +3
C) +5
D) +4
Answer:<\/strong> C
Explanation:<\/strong> x+3(\u22122)=\u22121\u21d2x=+5x + 3(-2) = -1 \\Rightarrow x = +5x+3(\u22122)=\u22121\u21d2x=+5<\/p>\n\n\n\n

63. Which of the following is an example of oxidation by loss of hydrogen?<\/mark><\/strong>
A) CH\u2084 \u2192 CH\u2083OH
B) H\u2082S \u2192 S
C) H\u2082 \u2192 2H\u207a
D) NH\u2083 \u2192 N\u2082
Answer:<\/strong> B
Explanation:<\/strong> Loss of H indicates oxidation.<\/p>\n\n\n\n

64. Which is an example of reduction by gain of hydrogen?<\/mark><\/strong>
A) N\u2082 \u2192 NH\u2083
B) H\u2082S \u2192 S
C) Fe\u00b2\u207a \u2192 Fe\u00b3\u207a
D) Cl\u2082 \u2192 2Cl\u207b
Answer:<\/strong> A
Explanation:<\/strong> N\u2082 gains hydrogen forming NH\u2083 (reduction).<\/p>\n\n\n\n

65. Oxidation number of P in P\u2082O\u2085 is:<\/mark><\/strong>
A) +3
B) +4
C) +5
D) +2
Answer:<\/strong> C
Explanation:<\/strong> 2x+5(\u22122)=0\u21d2x=+52x + 5(-2) = 0 \\Rightarrow x = +52x+5(\u22122)=0\u21d2x=+5<\/p>\n\n\n\n

66. Oxidation number of Cr in Cr\u2082O\u2083 is:<\/mark><\/strong>
A) +2
B) +3
C) +6
D) +4
Answer:<\/strong> B
Explanation:<\/strong> 2x+3(\u22122)=0\u21d2x=+32x + 3(-2) = 0 \\Rightarrow x = +32x+3(\u22122)=0\u21d2x=+3<\/p>\n\n\n\n

67. Oxidation number of Mn in Mn\u2082O\u2087 is:<\/mark><\/strong>
A) +4
B) +6
C) +7
D) +3
Answer:<\/strong> C
Explanation:<\/strong> 2x+7(\u22122)=0\u21d2x=+72x + 7(-2) = 0 \\Rightarrow x = +72x+7(\u22122)=0\u21d2x=+7<\/p>\n\n\n\n

68. Oxidation number of Cl in Cl\u2082O\u2087 is:<\/mark><\/strong>
A) +5
B) +7
C) +6
D) +4
Answer:<\/strong> B
Explanation:<\/strong> 2x+7(\u22122)=0\u21d2x=+72x + 7(-2) = 0 \\Rightarrow x = +72x+7(\u22122)=0\u21d2x=+7<\/p>\n\n\n\n

69. Which is not a redox reaction?<\/mark><\/strong>
A) NaOH + HCl \u2192 NaCl + H\u2082O
B) Zn + H\u2082SO\u2084 \u2192 ZnSO\u2084 + H\u2082
C) Fe + CuSO\u2084 \u2192 FeSO\u2084 + Cu
D) 2H\u2082 + O\u2082 \u2192 2H\u2082O
Answer:<\/strong> A
Explanation:<\/strong> Neutralization reaction, no electron transfer.<\/p>\n\n\n\n

70. Oxidation number of carbon in HCOOH is:<\/mark><\/strong>
A) +1
B) +2
C) 0
D) +3
Answer:<\/strong> +2
Explanation:<\/strong> +1+x+2(\u22122)+(+1)=0\u21d2x=+2+1 + x + 2(-2) + (+1) = 0 \\Rightarrow x = +2+1+x+2(\u22122)+(+1)=0\u21d2x=+2<\/p>\n\n\n\n

71. Oxidation number of chlorine in ClO\u2083\u207b is:<\/mark><\/strong>
A) +3
B) +5
C) +7
D) +1
Answer:<\/strong> B
Explanation:<\/strong> x+3(\u22122)=\u22121\u21d2x=+5x + 3(-2) = -1 \\Rightarrow x = +5x+3(\u22122)=\u22121\u21d2x=+5<\/p>\n\n\n\n

72. Oxidation number of S in H\u2082SO\u2083 is:<\/mark><\/strong>
A) +4
B) +6
C) +2
D) +3
Answer:<\/strong> A
Explanation:<\/strong> 2(+1)+x+3(\u22122)=0\u21d2x=+42(+1) + x + 3(-2) = 0 \\Rightarrow x = +42(+1)+x+3(\u22122)=0\u21d2x=+4<\/p>\n\n\n\n

73. Oxidation number of N in N\u2082H\u2084 (hydrazine) is:<\/mark><\/strong>
A) +1
B) -2
C) -1
D) 0
Answer:<\/strong> C
Explanation:<\/strong> 2x+4(+1)=0\u21d2x=\u22122\u00a0per\u00a0molecule,\u00a0\u22121\u00a0per\u00a0N2x + 4(+1) = 0 \\Rightarrow x = -2 \\text{ per molecule, } -1 \\text{ per N}2x+4(+1)=0\u21d2x=\u22122\u00a0per\u00a0molecule,\u00a0\u22121\u00a0per\u00a0N<\/p>\n\n\n\n

74. Oxidation number of C in CO is:<\/mark><\/strong>
A) +1
B) +2
C) +4
D) -2
Answer:<\/strong> B
Explanation:<\/strong> x+(\u22122)=0\u21d2x=+2x + (-2) = 0 \\Rightarrow x = +2x+(\u22122)=0\u21d2x=+2<\/p>\n\n\n\n

75. Oxidation number of Fe in FeCl\u2083 is:<\/mark><\/strong>
A) +2
B) +3
C) +1
D) 0
Answer:<\/strong> B
Explanation:<\/strong> x+3(\u22121)=0\u21d2x=+3x + 3(-1) = 0 \\Rightarrow x = +3x+3(\u22121)=0\u21d2x=+3<\/p>\n\n\n\n

76. Oxidation number of Cu in Cu\u2082O is:<\/mark><\/strong>
A) +1
B) +2
C) 0
D) +3
Answer:<\/strong> A
Explanation:<\/strong> 2x+(\u22122)=0\u21d2x=+12x + (-2) = 0 \\Rightarrow x = +12x+(\u22122)=0\u21d2x=+1<\/p>\n\n\n\n

77. Oxidation number of Cu in CuO is:<\/mark><\/strong>
A) +1
B) +2
C) 0
D) +3
Answer:<\/strong> B
Explanation:<\/strong> x+(\u22122)=0\u21d2x=+2x + (-2) = 0 \\Rightarrow x = +2x+(\u22122)=0\u21d2x=+2<\/p>\n\n\n\n

78. The oxidizing agent in<\/mark><\/strong>
2H\u2082O\u2082 \u2192 2H\u2082O + O\u2082 is:
A) H\u2082O
B) H\u2082O\u2082
C) O\u2082
D) None
Answer:<\/strong> B
Explanation:<\/strong> H\u2082O\u2082 decomposes; it acts as both oxidizing and reducing agent.<\/p>\n\n\n\n

79. In a redox reaction, the sum of oxidation numbers of all atoms in a neutral compound is:<\/mark><\/strong>
A) +1
B) 0
C) -1
D) Depends on element
Answer:<\/strong> B
Explanation:<\/strong> For a neutral compound, total oxidation number = 0.<\/p>\n\n\n\n

80. Oxidation number of N in NH\u2082OH is:<\/mark><\/strong>
A) +1
B) -1
C) -3
D) 0
Answer:<\/strong> -1
Explanation:<\/strong> x+3(+1)+(\u22122)+(+1)=0\u21d2x=\u22121x + 3(+1) + (-2) + (+1) = 0 \\Rightarrow x = -1x+3(+1)+(\u22122)+(+1)=0\u21d2x=\u22121<\/p>\n\n\n\n

81. Which of the following involves no change in oxidation number?<\/strong>
<\/mark>A) 2H\u2082 + O\u2082 \u2192 2H\u2082O
B) BaCl\u2082 + H\u2082SO\u2084 \u2192 BaSO\u2084 + 2HCl
C) Zn + H\u2082SO\u2084 \u2192 ZnSO\u2084 + H\u2082
D) Cu + 2AgNO\u2083 \u2192 Cu(NO\u2083)\u2082 + 2Ag
Answer:<\/strong> B
Explanation:<\/strong> Double displacement, no redox change.<\/p>\n\n\n\n

82. Oxidation number of S in Na\u2082S\u2082O\u2083 (thiosulfate) is:<\/strong>
<\/mark>A) +2
B) +2 and +6
C) +2 average
D) +3
Answer:<\/strong> C
Explanation:<\/strong> Average oxidation state of S = +2; actual: +2 and +6.<\/p>\n\n\n\n

83. Oxidation number of Cl in KClO is:<\/strong>
<\/mark>A) +1
B) +3
C) +5
D) +7
Answer:<\/strong> A
Explanation:<\/strong> +1+x+(\u22122)=0\u21d2x=+1+1 + x + (-2) = 0 \\Rightarrow x = +1+1+x+(\u22122)=0\u21d2x=+1<\/p>\n\n\n\n

84. Oxidation number of Br in BrO\u2083\u207b is:<\/strong>
<\/mark>A) +1
B) +3
C) +5
D) +7
Answer:<\/strong> C
Explanation:<\/strong> x+3(\u22122)=\u22121\u21d2x=+5x + 3(-2) = -1 \\Rightarrow x = +5x+3(\u22122)=\u22121\u21d2x=+5<\/p>\n\n\n\n

85. Oxidation number of S in SF\u2086 is:<\/strong>
<\/mark>A) +4
B) +6
C) +2
D) 0
Answer:<\/strong> B
Explanation:<\/strong> x+6(\u22121)=0\u21d2x=+6x + 6(-1) = 0 \\Rightarrow x = +6x+6(\u22121)=0\u21d2x=+6<\/p>\n\n\n\n

86. Oxidation number of N in N\u2082O\u2083 is:<\/strong>
<\/mark>A) +1
B) +2
C) +3
D) +4
Answer:<\/strong> C
Explanation:<\/strong> 2x+3(\u22122)=0\u21d2x=+32x + 3(-2) = 0 \\Rightarrow x = +32x+3(\u22122)=0\u21d2x=+3<\/p>\n\n\n\n

87. Oxidation number of N in NO is:<\/strong>
<\/mark>A) +1
B) +2
C) +3
D) +4
Answer:<\/strong> B
Explanation:<\/strong> x+(\u22122)=0\u21d2x=+2x + (-2) = 0 \\Rightarrow x = +2x+(\u22122)=0\u21d2x=+2<\/p>\n\n\n\n

88. Oxidation number of N in N\u2082O\u2085 is:<\/strong>
<\/mark>A) +3
B) +4
C) +5
D) +2
Answer:<\/strong> C
Explanation:<\/strong> 2x+5(\u22122)=0\u21d2x=+52x + 5(-2) = 0 \\Rightarrow x = +52x+5(\u22122)=0\u21d2x=+5<\/p>\n\n\n\n

89. Oxidation number of Cr in CrO\u2084\u00b2\u207b is:<\/strong>
<\/mark>A) +3
B) +4
C) +6
D) +5
Answer:<\/strong> C
Explanation:<\/strong> x+4(\u22122)=\u22122\u21d2x=+6x + 4(-2) = -2 \\Rightarrow x = +6x+4(\u22122)=\u22122\u21d2x=+6<\/p>\n\n\n\n

90. Oxidation number of Cr in Cr\u2082O\u2087\u00b2\u207b is:<\/strong>
<\/mark>A) +4
B) +6
C) +3
D) +2
Answer:<\/strong> B
Explanation:<\/strong> 2x+7(\u22122)=\u22122\u21d2x=+62x + 7(-2) = -2 \\Rightarrow x = +62x+7(\u22122)=\u22122\u21d2x=+6<\/p>\n\n\n\n

91. Oxidation number of Cl in Cl\u2082O is:<\/strong>
<\/mark>A) +1
B) +2
C) +4
D) +3
Answer:<\/strong> +1
Explanation:<\/strong> 2x+(\u22122)=0\u21d2x=+12x + (-2) = 0 \\Rightarrow x = +12x+(\u22122)=0\u21d2x=+1<\/p>\n\n\n\n

92. Oxidation number of Cl in ClO\u2082\u207b is:<\/strong>
<\/mark>A) +1
B) +3
C) +5
D) +7
Answer:<\/strong> +3
Explanation:<\/strong> x+2(\u22122)=\u22121\u21d2x=+3x + 2(-2) = -1 \\Rightarrow x = +3x+2(\u22122)=\u22121\u21d2x=+3<\/p>\n\n\n\n

93. In the reaction<\/strong>
<\/mark>2Na + Cl\u2082 \u2192 2NaCl,
which is oxidized?
A) Na
B) Cl\u2082
C) NaCl
D) None
Answer:<\/strong> A
Explanation:<\/strong> Na \u2192 Na\u207a + e\u207b (oxidation).<\/p>\n\n\n\n

94. Which is reduced in the same reaction?<\/strong>
<\/mark>A) Na
B) Cl\u2082
C) NaCl
D) None
Answer:<\/strong> B
Explanation:<\/strong> Cl\u2082 + 2e\u207b \u2192 2Cl\u207b (reduction).<\/p>\n\n\n\n

95. Oxidation number of Mn in KMnO\u2084 changes from +7 to +2 in acidic medium. The number of electrons gained per Mn atom is:<\/strong>
<\/mark>A) 3
B) 5
C) 2
D) 4
Answer:<\/strong> B
Explanation:<\/strong> +7 \u2192 +2 = gain of 5 electrons.<\/p>\n\n\n\n

96. In the redox reaction, oxidation and reduction occur:<\/strong>
<\/mark>A) Separately
B) Simultaneously
C) Independently
D) Not at all
Answer:<\/strong> B
Explanation:<\/strong> Oxidation and reduction always occur together.<\/p>\n\n\n\n

97. The species that accepts electrons is called:<\/strong>
<\/mark>A) Oxidizing agent
B) Reducing agent
C) Catalyst
D) Base
Answer:<\/strong> A
Explanation:<\/strong> Accepting electrons = reduction = oxidizing agent.<\/p>\n\n\n\n

98. The species that donates electrons is called:<\/strong>
<\/mark>A) Oxidizing agent
B) Reducing agent
C) Acid
D) Catalyst
Answer:<\/strong> B
Explanation:<\/strong> Donating electrons = oxidation = reducing agent.<\/p>\n\n\n\n

99. In redox reactions, the total increase in oxidation number equals:<\/strong>
<\/mark>A) Total decrease in oxidation number
B) Zero
C) Sum of oxidation states
D) None
Answer:<\/strong> A
Explanation:<\/strong> Electrons lost = electrons gained.<\/p>\n\n\n\n

100. Which of the following best defines a redox reaction?<\/strong>
<\/mark>A) Reaction involving acids and bases
B) Reaction involving exchange of ions
C) Reaction involving oxidation and reduction simultaneously
D) Reaction involving proton transfer
Answer:<\/strong> C
Explanation:<\/strong> Redox reaction = simultaneous oxidation and reduction due to electron transfer.<\/p>\n","protected":false},"excerpt":{"rendered":"

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