Chemistry MCQ with Answer and Explanation : Oxidation and Reduction.

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Question 41:

In the reaction H2+F2→2HFH2​+F2​→2HF, which species is oxidized?
A) H2H2​
B) F2F2​
C) HFHF
D) None of the above

Answer: A) H2H2​

Explanation: Hydrogen is oxidized as it goes from 0 in H2H2​ to +1 in HFHF.

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Question 42:

Which of the following is the correct definition of oxidation?
A) Gain of protons.
B) Loss of neutrons.
C) Loss of electrons.
D) Gain of electrons.

Answer: C) Loss of electrons.

Explanation: Oxidation is defined as the loss of electrons, which increases the oxidation state.

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Question 43:

In the reaction 2Ag++Cu→2Ag+Cu2+2Ag++Cu→2Ag+Cu2+, which species acts as the reducing agent?
A) Ag+Ag+
B) CuCu
C) AgAg
D) Cu2+Cu2+

Answer: B) CuCu

Explanation: Copper is oxidized and acts as the reducing agent by donating electrons to silver ions.

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Question 44:

What is the oxidation state of chlorine in Cl2Cl2​?
A) +1
B) 0
C) -1
D) +2

Answer: B) 0

Explanation: In elemental form, the oxidation state of chlorine is 0.

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Question 45:

Which of the following describes a reduction reaction?
A) Zn2++2e−→ZnZn2++2e−→Zn
B) H2+2e−→2H−H2​+2e−→2H−
C) O2+4e−→2O2−O2​+4e−→2O2−
D) All of the above

Answer: D) All of the above

Explanation: Each of the reactions shows a gain of electrons, which is the definition of reduction.

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Question 46:

In which of the following compounds does sulfur have an oxidation state of +4?
A) SO2SO2​
B) H2SH2​S
C) SO3SO3​
D) S8S8​

Answer: A) SO2SO2​

Explanation: In sulfur dioxide (SO2SO2​), sulfur has an oxidation state of +4.

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Question 47:

Which reaction represents a redox process?
A) NaOH+HCl→NaCl+H2ONaOH+HCl→NaCl+H2​O
B) CaCO3→CaO+CO2CaCO3​→CaO+CO2​
C) Fe3++3e−→FeFe3++3e−→Fe
D) H2+Cl2→2HClH2​+Cl2​→2HCl

Answer: C) Fe3++3e−→FeFe3++3e−→Fe

Explanation: This reaction involves a change in oxidation states, showing that it is a redox process.

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Question 48:

In the reaction 4Al+3O2→2Al2O34Al+3O2​→2Al2​O3​, which substance is reduced?
A) Al
B) O
C) Al2O3Al2​O3​
D) None of the above

Answer: B) O

Explanation: Oxygen is reduced from 0 in O2O2​ to -2 in Al2O3Al2​O3​.

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Question 49:

What is the oxidation state of nitrogen in NO3−NO3−​?
A) +1
B) +3
C) +5
D) +4

Answer: C) +5

Explanation: In the nitrate ion (NO3−NO3−​), nitrogen has an oxidation state of +5.

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Question 50:

Which of the following is a common characteristic of both oxidation and reduction reactions?
A) They involve the transfer of electrons.
B) They occur independently of each other.
C) They always produce a gas.
D) None of the above.

Answer: A) They involve the transfer of electrons.

Explanation: Oxidation and reduction are always coupled processes involving electron transfer.