Redox Reactions Multiple Choice Questions and Answers for Practice

16. The oxidation number of an element in a compound is evaluated on the basis of certain rules. Which of the following rules is not correct in this respect?

1. The oxidation number of hydrogen is always +1.
2. The algebraic sum of all the oxidation numbers in a compound is zero.
3. An element in the free or the uncombined state bears oxidation number zero.
4. In all its compounds, the oxidation number of fluorine is -1.

17. The largest oxidation number exhibited by an element depends on its outer electronic configuration. With which of the following outer electronic configurations the element will exhibit largest oxidation number?

1. 3d¹4s²
2. 3d² 4s²
3. 3d⁵4s¹
4. 3d⁵4s²

18. Which of the following elements does not show disproportionation tendency?

1. Cl
2. Br
3. F
4. I

19. What is known as Autooxidation?

1. Formation of H₂O by the oxidation of H₂O₂
2. Formation of H₂O₂ by the oxidation of H₂O
3. Both (1) and (2) are true
4. None of the above

20. The tendency of an electrode to lose electrons is known as

1. Electrode Potential
2. Reduction Potential
3. Oxidation Potential
4. E.M.F.

21. What is n-factor?

1. Equal to product of Number of moles of electrons when Lost or gained by one mole of reductant or oxidant
2. When Number of moles of electrons Lost or gained by one mole of reductant or oxidant is not same.
3. Equal to Number of moles of electrons Lost or gained by one mole of reductant or oxidant
4. None of the above

22. Oxidation numbers of P in PO₄^3-, of S in SO₄^2- and that of Cr in Cr₂O₇^2- are respectively

1. +3, +6 and +5
2. +5, +3 and +6
3. –3, +6 and +6
4. +5, +6 and +6

23. Oxidation state of Fe in Fe₃O₄ is

1. 5/4
2. 4/5
3. 3/2
4. 8/3

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

1. CO₂
2. ClO₂
3. NO₂
4. SO₂

25. For the feasibility of redox reaction in a cell, the e.m.f. should be

1. Positive
2. Fixed
3. Zero
4. Negative