Chemistry MCQ with Answer and Explanation : Oxidation and Reduction.

Question 51:

Which of the following is a characteristic of oxidation?
A) Gain of electrons
B) Loss of hydrogen
C) Gain of oxygen
D) Both B and C

Answer: D) Both B and C

Explanation: Oxidation can involve both the loss of hydrogen and the gain of oxygen.

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Question 52:

In the reaction 2FeCl3+Sn→2FeCl2+SnCl22FeCl3​+Sn→2FeCl2​+SnCl2​, which species is reduced?
A) FeCl3FeCl3​
B) FeCl2FeCl2​
C) SnSn
D) SnCl2SnCl2​

Answer: A) FeCl3FeCl3​

Explanation: Iron in FeCl3FeCl3​ is reduced from +3 to +2 in FeCl2FeCl2​.

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Question 53:

Which element has the highest oxidation state in K2Cr2O7K2​Cr2​O7​?
A) K
B) Cr
C) O
D) None of the above

Answer: B) Cr

Explanation: In potassium dichromate (K2Cr2O7K2​Cr2​O7​), chromium has an oxidation state of +6.

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Question 54:

What is the oxidation state of phosphorus in H3PO2H3​PO2​?
A) +1
B) +3
C) +5
D) 0

Answer: B) +3

Explanation: In phosphorous acid (H3PO2H3​PO2​), phosphorus has an oxidation state of +3.

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Question 55:

Which of the following compounds is a common reducing agent?
A) H2O2H2​O2​
B) Fe3+Fe3+
C) NaNa
D) Cl2Cl2​

Answer: C) NaNa

Explanation: Sodium is a strong reducing agent because it readily donates electrons.

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Question 56:

In the reaction 2H2+O2→2H2O2H2​+O2​→2H2​O, what is the change in oxidation state of oxygen?
A) 0 to -1
B) 0 to -2
C) +1 to -2
D) 0 to +1

Answer: B) 0 to -2

Explanation: Oxygen is reduced as it goes from 0 in O2O2​ to -2 in H2OH2​O.

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Question 57:

In a galvanic cell, the anode is the site of:
A) Reduction
B) Oxidation
C) Neutralization
D) Electrolysis

Answer: B) Oxidation

Explanation: The anode is where oxidation occurs in a galvanic cell.

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Question 58:

Which of the following is an example of a redox reaction?
A) 2Na+Cl2→2NaCl2Na+Cl2​→2NaCl
B) HCl+NaOH→NaCl+H2OHCl+NaOH→NaCl+H2​O
C) CaCO3→CaO+CO2CaCO3​→CaO+CO2​
D) H2+O2→H2OH2​+O2​→H2​O

Answer: A) 2Na+Cl2→2NaCl2Na+Cl2​→2NaCl

Explanation: Sodium is oxidized and chlorine is reduced in this reaction, indicating it is a redox reaction.

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Question 59:

What is the oxidation state of sulfur in H2SO3H2​SO3​?
A) +4
B) +6
C) -2
D) 0

Answer: A) +4

Explanation: In sulfurous acid (H2SO3H2​SO3​), sulfur has an oxidation state of +4.

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Question 60:

Which of the following ions is the strongest oxidizing agent?
A) Fe3+Fe3+
B) Cl−Cl−
C) MnO4−MnO4−​
D) I−I−

Answer: C) MnO4−MnO4−​

Explanation: The permanganate ion is a strong oxidizing agent, particularly in acidic solutions.