MCQ Questions for Class 11 Chemistry Chapter 8 Redox Reactions with Answers

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Redox Reactions Class 11 MCQs Questions with Answers

Multiple Choice Type Questions

Question 1.
The oxidation of sulphur in the anions SO\(_{3}^{2-}\), S2O\(_{4}^{2-}\) and S2O\(_{6}^{2-}\) follow the order
(a) S2O\(_{4}^{2-}\) < SO\(_{3}^{2}\) < S2O\(_{6}^{2}\)
(b) SO\(_{3}^{2-}\) < S2O\(_{4}^{2-}\) < S2O\(_{6}^{2-}\)
(c) S2O\(_{4}^{2-}\) < S2O\(_{6}^{2}\) < SO\(_{3}^{2-}\)
(d) S2O\(_{6}^{2}\) < S2O\(_{4}^{2-}\) < SO\(_{3}^{2-}\)

Answer

Answer: (a) S2O\(_{4}^{2-}\) < SO\(_{3}^{2}\) < S2O\(_{6}^{2}\)


Question 2.
Which of the following is a redox reaction?
(a) NaCl + KNO3 → NaNO3 + KCl
(b) CaC2O4 + 2HCl → CaCl2 + H2C2O4
(c) Mg(OH)2 + 2NH4Cl → MgCl2 + 2NH4OH
(d) Zn + 2AgCN → 2Ag + Zn (CN)2

Answer

Answer: (d) Zn + 2AgCN → 2Ag + Zn (CN)2


Question 3.
(x) MnO\(_{4}^{-}\) + (y) H2O2 → 2 Mn2+ + 5H2O + 9O2 + 2e
In this reaction the value of (x)
(a) 2, 5, 6
(b) 5, 2, 9
(c) 3, 5, 5
(d) 2, 6, 6

Answer

Answer: (a) 2, 5, 6


Question 4.
When KMnO4 acts as an oxidising agent and ultimately forms MnO\(_{4}^{2-}\), MnO2, Mn2O3 and Mn2+ then the no. of electrons transferred in each case respectively is
(a) 4, 3, 1, 5
(b) 1, 5, 3, 7
(c) 1, 3, 4, 5
(d) 3, 5, 7, 1

Answer

Answer: (c) 1, 3, 4, 5


Question 5.
The value of x & y in the following redox reaction-
xCl2 + 6OH → ClO\(_{3}^{-}\) + yCl + 3H2O are
(a) x = 2, y = 4
(b) x = 5, y = 3
(c) x = 3, y = 5
(d) x = 4, y = 2

Answer

Answer: (c) x = 3, y = 5


Question 6.
The oxidation state of chromium in
[Cr (P Ph3) (CO)3] is
(a) + 3
(b) +8
(c) Zero
(d) +5

Answer

Answer: (c) Zero


Question 7.
Which of the following is not a reducing agent?
(a) SO2
(b) H2O2
(c) CO2
(d) NO\(_{2}^{-}\)

Answer

Answer: (c) CO2


Question 8.
Number of moles of K2Cr2O7 reduced by 1 mole of Sn2+ is
(a) \(\frac {1}{6}\)
(b) \(\frac {1}{3}\)
(c) \(\frac {2}{3}\)
(d) 1

Answer

Answer: (b) \(\frac {1}{3}\)


Question 9.
For the redox reaction-
MnO\(_{4}^{-}\) + C2O\(_{4}^{2-}\) + H+ → Mn2+ + CO2 + H2O
correct stoichiometric coefficients of MnO\(_{4}^{-}\), C2O\(_{4}^{2-}\), H+ are
(a) 2, 5, 16
(b) 16, 5, 2
(c) 5, 11, 2
(d) 2, 16, 5

Answer

Answer: (a) 2, 5, 16


Question 10.
The oxidation number of iron in Fe3O4 is
(a) +2
(b) +3
(c) \(\frac {8}{3}\)
(d) \(\frac {2}{3}\)

Answer

Answer: (c) \(\frac {8}{3}\)


Question 11.
Which is a redox reaction?
(a) H2SO4 + 2NaOH → Na2SO4 + 2H2O
(b) BaCl2 + H2SO4 → BaSO4 + 2HCl
(c) CH3COOH + C2H5OH → CH3COOC2H5 + H2O
(d) 2FeCl3 + SnCl2 → 2FeCl2 + SnCl4

Answer

Answer: (d) 2FeCl3 + SnCl2 → 2FeCl2 + SnCl4


Question 12.
A compound contains atoms of three elements -A, B & C. If the oxidation number of A is +2, B is +5 and that of C is -2 the possible formula of the compound is-
(a) A3(BC4)2
(b) A3(B4C)2
(c) ABC2
(d) A3(BC3)2

Answer

Answer: (a) A3(BC4)2


Question 13.
Oxidation state of osmium (Os) in OsO4 is
(a) +7
(b) + 6
(c) +4
(d) + 8

Answer

Answer: (d) + 8


Question 14.
Oxidation number of sodium in sodium amalgam is
(a) +1
(b) 0
(c) – 1
(d) + 2

Answer

Answer: (b) 0


Question 15.
Oxidation number of cobalt in K[Co(CO)4] is
(a) +1
(b) +3
(c) – 1
(d) – 3

Answer

Answer: (c) – 1


Question 16.
The oxidation state of chromium in Cr(CO)6 is
(a) 0
(b) +7
(c) -2
(d) +6

Answer

Answer: (a) 0


Question 17.
The reaction 3ClO (aq) → CIO\(_{3}^{-}\) (aq) + 2Cl(aq) is an example of-
(a) Oxidation reaction
(b) Reduction reaction
(c) Disproportionation reaction
(d) Decomposition reaction

Answer

Answer: (c) Disproportionation reaction


Question 18.
Among the following, identify the species with an atom in + 6 oxidation state:
(a) MnO\(_{4}^{-}\)
(b) Cr(CN)\(_{6}^{3-}\)
(c) NiF\(_{6}^{2-}\)
(d) CrO2Cl2

Answer

Answer: (d) CrO2Cl2


Question 19.
For the reaction:
Mx+ + MnO\(_{4}^{-}\) → MO\(_{3}^{-}\) + Mn2+ + \(\frac {2}{3}\)O2
if one mole of MnO\(_{4}^{-}\) oxidised 1.67 moles of Mx+ to MO\(_{3}^{-}\), then the value of x in the reaction will be
(a) 5
(b) 3
(c) 2
(d) 1

Answer

Answer: (c) 2


Question 20.
The oxidation number of sulphur in S8, S2F2, H2S respectively are
(a) 0, +1, -2
(b) +2, +1, -2
(c) 0, +1, +2
(d) -2, +1, -2

Answer

Answer: (a) 0, +1, -2


Fill in the blanks

Question 1.
A chemical reaction involving ………………….. is known as oxidation.

Answer

Answer: Loss of electrons


Question 2.
The algebraic sum of the oxidation number of all the atoms in a compound must be …………………..

Answer

Answer: Zero


Question 3.
In all its compounds, fluorine has an oxidation number of …………………..

Answer

Answer: -1


Question 4.
In LiH, NaH and CaH2, the oxidation no. of Hydrogen is …………………..

Answer

Answer: -1


Question 5.
In oxygen difluoride (OF2) the oxidation number of oxygen is …………………..

Answer

Answer: +2


Question 6.
Na+ has an oxidation number of …………………..

Answer

Answer: +1


Question 7.
Each atom in H2, O2, Cl2, O3, P4, S8, Na, Mg, Al has the oxidation number …………………..

Answer

Answer: Zero


Question 8.
The standard electrode potential (E°) of hydrogen electrode is ………………….. volts.

Answer

Answer: 0.00


Question 9.
The oxidation state of hydrogen in metal hydride is …………………..

Answer

Answer: -1


Question 10.
The oxidation number of oxygen in a water molecules is …………………..

Answer

Answer: -2


Write True / False

Question 1.
Oxidation involves a loss of electrons.

Answer

Answer: True


Question 2.
Oxidising agents looses electrons.

Answer

Answer: False


Question 3.
In the reaction Cu2+(aq) + Zn(s) → Zn2+(aq) + Cu(s) Zn acts as a reducing agent.

Answer

Answer: True


Question 4.
The oxidation state of oxygen in H2O2 is -1.

Answer

Answer: True


Question 5.
The oxidation state of C in CHCl3 is 4.

Answer

Answer: False


Question 6.
The reaction NH3 + HCl → NH4Cl is a redox reaction.

Answer

Answer: False


Question 7.
During oxidation, oxidation number of the element decrease.

Answer

Answer: False


Question 8.
There is no change in the oxidation number of hydrogen in methane under combustion reaction.

Answer

Answer: True


Question 9.
In CO2, the oxidation state of carbon is -2.

Answer

Answer: False


Question 10.
Combination of an electrode and the solutio’n in which it is dipped is called a half cell.

Answer

Answer: True


Match the Following

Column I Column II
1. Electrochemical cell (a) Literates Cl2 from Cl ions.
2. Electrolysis of fused sodium chloride (b) Reduced HgCl2 to Hg2Cl2
3. Fluorine (c) Hydrogen gas.
4. Zinc, magnesium, iron etc react with dil H2SO4 to evolve (d) Convert chemical energy into electrical energy.
5. Stannous chloride (e) Produce Cl2 at the cathode.
6. Oxidation no. of c in CH3Cl (f) CO2
7. The ox. no. of Cr in Cr(CO)6 is (g) +6
8. The reducing agent is (h) -2
9. Ox. no. of Cr in CrO5 is (i) -1
10. The ox. no. of oxygen in H2O2 is (j) 0
Answer

Answer:

Column I Column II
1. Electrochemical cell (d) Convert chemical energy into electrical energy.
2. Electrolysis of fused sodium chloride (e) Produce Cl2 at the cathode.
3. Fluorine (a) Literates Cl2 from Cl ions.
4. Zinc, magnesium, iron etc react with dil H2SO4 to evolve (c) Hydrogen gas.
5. Stannous chloride (b) Reduced HgCl2 to Hg2Cl2.
6. Oxidation no. of c in CH3Cl (h) -2
7. The ox. no. of Cr in Cr(CO)6 is (j) 0
8. The reducing agent is (f) CO2
9. Ox. no. of Cr in CrO5 is (g) +6
10. The ox. no. of oxygen in H2O2 is (i) -1

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