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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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