Free Oxidation and Reduction MCQs with Answers

• A. N
• B. Cr
• C. S
• D. Mn

Explanation: The highest common oxidation number listed is Mn(+7), as in permanganate, while N commonly reaches +5 and Cr and S commonly reach +6.

• A. Ag
• B. A
• C. Au
• D. Cu

Explanation: Gold is below the other listed metals in the activity series, so metals such as aluminium, copper and silver can displace gold ions from…

• A. S
• B. SO2
• C. H2SO3
• D. H2S

Explanation: H2S is correct because it is the product formed when Hl reduces H2SO4 due to the reduction of sulfur in sulfuric acid.

• A. -2
• B. -4
• C. -5
• D. -1

Explanation: as K belongs to group 1A so it has 1 oxidation number which is why Oxygen will also have one oxidation number, but in negative.

• A. +7
• B. +3
• C. +6
• D. +5

Explanation: a) +7:The oxidation number of iodine in periodic acid (H5IO6) is indeed +7.

• A. +1
• B. -2
• C. -1
• D. -1/2

Explanation: The explanation for this question will be added soon.

• A. Oxidation potential
• B. Reduction potential
• C. Redox potential
• D. EMF of cell

Explanation: The stronger the oxidizing agent, the greater will be its reduction potential.

• A. Anode
• B. Cathode
• C. Salt bridge
• D. None of these options are correct

Explanation: Oxidation occurs at the anode and reduction occurs at the cathode. Since the reaction at the anode is the source of electrons for the…

• A. +1
• B. +2
• C. 0
• D. -1

Explanation: Free state means uncombined state, i.e., atomic state. In an uncombined state the oxidation number will always be zero.

• A. Anode
• B. Cathode
• C. SHE
• D. Salt bridge

Explanation: Reduction happens at the negative cathode because this is where positive ions gain electrons.

• A. Anode
• B. Cathode
• C. SHE
• D. Salt bridge

Explanation: During electrolysis, reduction occurs at cathode

• A. 7
• B. -7
• C. 6
• D. -6

Explanation: The oxidation number of Mn in MnO4- can be calculated by considering the overall charge of the compound and assigning oxidation numbers to…

• A. Gain
• B. Lost
• C. Accept
• D. Produced

Explanation: The number of charges present on a cation depends on the number of electrons lost by the atom.

• A. Unity
• B. Positive
• C. Zero
• D. Negative

Explanation: Option C is correct since a free state means an 'uncombined state', i.e., atomic state.

• A. Discharged at anode
• B. Discharge at cathode
• C. Do not discharge
• D. None of these options is correct

Explanation: At Cathode Sodium is not discharged but H2 gas is discharged. Sodium remains in the solution and more H2 gas is formed at the end of…

• A. Reduction
• B. Hydrolysis
• C. Dehydration
• D. Oxidation

Explanation: K2Cr2O7 and H2SO4 lose their oxygen while acting as a reagent hence leading to the "oxidation" of the reactant. Hence, the answer will be D.

• A. Corrode slowly
• B. Does not corrode easily
• C. Corrode rapidly
• D. None of these

Explanation: Pure metals do not corrode. The absence of impurities and the ability to develop protective surface layers make pure metals less prone to…

• A. Nitrous oxide
• B. Nitric oxide
• C. Nitrogen peroxide
• D. Nitrous anhydride

Explanation: Nitric oxide =+2Nitrous oxide = +1Nitrous anhydride= +3Nitrogen peroxide= +5

• A. ±2
• B. +4 and +6
• C. None of these
• D. Both A and B

Explanation: In H₂SO₄, the oxidation number of S is +6.In H₂SO₃, the oxidation number of S is +4.In Na₂S₂O₃, the oxidation number of S is +2.

• A. Redox Potential
• B. Oxidation Potential
• C. EMF of the cell
• D. Reduction Potential

Explanation: A stronger oxidizing agent means it undergoes reduction more easily and thus has greater standard reduction potential.