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Chemistry
Redox Reaction
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1
When sulphur dioxide is passed in an acidified K2Cr2O7 solution, the oxidation state of sulphur is changed from;
A
+4 to 0
B
+4 to +2
C
+4 to +6
D
+6 to +4
2
–3 oxidation state of nitrogen will be obtained in case of;
A
Ammonia (NH3)
B
Hydrazoic acid (HN3)
C
Nitric oxide (NO)
D
Nitrous oxide (N2O)
3
Given below are two statements: Statements I: A negative E° means that the redox couple is a stronger reducing agent than the H+/H2. Statements II: A positive E° means that the redox couple is a weaker reducing agent than the H+/H2.
A
Statement I is correct but Statement II is incorrect.
B
Statement I is incorrect but Statement II is correct.
C
Both Statement I and Statement II are correct.
D
Both Statement I and Statement II are incorrect.
4
Which of the following is a redox reaction?
A
K2SO4 + BaCl2 → BaSO4 + 2KCl
B
BaO + H2SO4 → BaSO4 + H2O
C
AgNO3 + NaCl → AgCl + NaNO3
D
2H2S + SO2 → 2H2O + 3S
5
In all of its compounds, oxidation state of oxygen may vary from;
A
+6 to –6
B
–2 to +2
C
+2 to +6
D
0 to –2
6
The oxidation state of Xe in Ba2XeO6 is:
A
0
B
+8
C
+6
D
+4
7
Standard reduction electrode potentials of three metals A, B and C are +0.5V, –3.0V & –1.2V respectively. The decreasing order of reducing powers of these metals is;
A
A > B > C
B
C > B > A
C
A > C > B
D
B > C > A
8
–3 oxidation state of nitrogen will be obtained in case of;
A
Ammonia (NH3)
B
Hydrazoic acid (HN3)
C
Nitric oxide (NO)
D
Nitrous oxide (N2O)
9
Match List-I with List-II. List-I (Compound) List-II (Average Oxidation state of central atom) A. H4P2O7 B. C3O4 C. H2S4O6 D. K2MnO4
A
A-III, B-I, C-II, D-IV
B
A-IV, B-III, C-II, D-I
C
A-II, B-III, C-IV, D-I
D
A-II, B-I, C-III, D-IV
10
Match the half-reactions (in column I) with change in oxidation number (in column II)
| Column I | Column II |
|---|---|
A | i 2 |
B | ii 8 |
C | iii 0 |
D | iv 3 |
A
A-(2), B-(4), C-(1), D-(3)
B
A-(4), B-(2), C-(1), D-(3)
C
A-(3), B-(1), C-(4), D-(2)
D
A-(2), B-(1), C-(3), D-(4)
11
Given below are two statements: Statements I: KMnO4 can work both as an oxidising as well as reducing agent. Statements II: The equation, Mg(s) + CuO(s) → MgO(s) + Cu(s) represents decomposition reaction. In the light of the above statements, choose the most appropriate answer:
A
Both Statement I and Statement II are correct.
B
Statement I is correct but Statement II is incorrect.
C
Statement I is incorrect but Statement II is correct.
D
Both Statement I and Statement II are incorrect.
12
Which of the following changes does not require only two electrons to occur?
A
S → S^2−
B
Cu → Cu^2+
C
Cl2 → 2Cl−
D
MnO4^2− → Mn^2+
13
Identify in which of the following reaction(s), H2O2 is being oxidized and choose the correct option. A. H2O2 + 2H+ + 2e− → 2H2O B. H2O2 → O2 + 2H+ + 2e− C. H2O2 + 2e− → 2OH−
A
Both A and C
B
Only B
C
Both A and B
D
Only C
14
The value of ‘n’ in the balanced reaction:
will be;
A
2
B
3
C
6
D
7
15
The correct order of electron releasing tendency of the given metals is;
A
Zn > Cu > Ag
B
Cu > Zn > Ag
C
Ag > Cu > Zn
D
Zn > Ag > Cu
16
In the reaction, 4Fe + 3O2 → 2Fe2O3, which of the following statements in incorrect?
A
It is a redox reaction
B
Iron acts as a reducing agent
C
O2 is oxidised
D
None of these
17
The oxidation number of Sulphur in S₈ and S₂F₂ respectively are
A
−2 and +2
B
0 and +2
C
0 and +1
D
−2 and 0
18
The number of electrons lost or gained during the change, Fe + H2O → Fe3O4 + H2 is;
A
2
B
4
C
6
D
8
19
The species undergoing oxidation in the following reaction is: 3SO3^2− + Cr2O7^2− + 8H+ → 3SO4^2− + 2Cr^3+ + 4H2O
A
H2O
B
SO3^2−
C
Cr2O7^2−
D
H+
20
The oxidation state of oxygen in the following reaction changes, K2O2 → KO2
A
From 0 to –1
B
From 0 to –2
C
From 0 to –1/2
D
From 0 to +1
21
Which of the following reactions is not a disproportionation reaction?
A
B
C
D
22
Zero oxidation state is present in:
A
O3
B
P4
C
S8
D
All of these
23
Which of the following can not act as reducing agent?
A
H2SO4
B
HClO3
C
H3PO2
D
Na2SO3
24
An element which never has a positive oxidation number in any of its compound is;
A
Boron
B
Oxygen
C
Chlorine
D
Fluorine
25
Arrange the following species in order of an increase in oxidation number of Mn; I. Mn2+ II. MnO2 III. KMnO4 IV. K2MnO4
A
I < II < III < IV
B
I < II < IV < III
C
II < III < I < IV
D
III < I < IV < II
26
In the given redox reaction: Cr2O7^2− + Fe2+ → Fe3+ + Cr3+ 1 mol of Cr2O7^2− oxidises:
A
1 mol of Fe2+
B
3 mol of Fe2+
C
4 mol of Fe2+
D
6 mol of Fe2+
27
Redox reaction is generally a/an;
A
proton transfer reaction.
B
ion combination reaction.
C
decomposition reaction.
D
electron transfer reaction.
28
Chlorine has +1 oxidation state in;
A
HCl
B
HClO4
C
ICl
D
Cl2O
29
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R): Assertion (A) : Equivalent weight of N2 in the reaction N2 + H2 → NH3 is 28/6. Reason (R): Equivalent weight = Molecular weight / number of e− lost or gained by 1 mol.
A
A is true but R is false.
B
A is false but R is true.
C
Both A and R are true and R is the correct explanation of A.
D
Both A and R are true but R is NOT the correct explanation of A.
30
Which of the following statements is correct about oxidation state of S in Na2S4O6?
A
All S-atoms are in +2.5 state
B
All S-atoms are in +2 state
C
Two S-atoms are in 0 state and other two, in +5 state
D
Two S-atoms are in –1 state and other two, in +6 state
31
Reaction V2O5 + 5Ca → 2V + 5CaO can be classified as;
A
Combination reaction
B
Disproportionation reaction
C
Decomposition reaction
D
Displacement reaction
32
An element which never has a positive oxidation number in any of its compound is;
A
Boron
B
Oxygen
C
Chlorine
D
Fluorine
33
The average oxidation state of Fe in Fe3O4 is:
A
+4/3
B
+8/3
C
+2/3
D
+5/3
34
Which of the following is the most powerful oxidising agent?
A
F2
B
O2
C
Cl2
D
Br2
35
The conversion of sugar C12H22O11 → CO2 is;
A
oxidation.
B
reduction.
C
neither oxidation nor reduction.
D
both oxidation and reduction
36
Zn rod is dipped in blue coloured solution of aqueous Cu(NO3)2. The incorrect statement among the following is;
A
Blue colour will get intensified
B
Zn rod will start dissolving
C
Cu metal will start depositing on Zn rod
D
Solution will remain electrically neutral
37
Match List-I with List-II. List-I (Reactions) (A) Combination reaction (B) Decomposition reaction (C) Metal displacement reaction (D) Non-metal displacement reaction List-II (Examples) (I) Fe + 2HCl → FeCl2 + H2 (II) C + O2 → CO2 (III) Cr2O3 + 2Al → Al2O3 + 2Cr (IV) 2NaH → 2Na + H2 Choose the correct answer from the options given below:
A
A-II, B-IV, C-III, D-I
B
A-I, B-III, C-IV, D-II
C
A-II, B-I, C-III, D-IV
D
A-III, B-IV, C-I, D-II
38
Given below are two statements: Assertion (A): In Na2O2, the oxidation state of each oxygen atom is –1. Reason (R): In peroxides, each oxygen atom is assigned an oxidation number of –1.
A
A is true but R is false.
B
A is false but R is true.
C
Both A and R are true and R is the correct explanation of A.
D
Both A and R are true and R is NOT the correct explanation of A.
39
Match List-I with List-II. List-I (Molecule) (A) KO3 (B) H2O2 (C) MgO (D) KO2 List-II (Oxidation state of oxygen) (I) –1 (II) –1/3 (III) –1/2 (IV) –2 Choose the correct answer from the options given below:
A
A-II, B-IV, C-III, D-I
B
A-I, B-II, C-IV, D-III
C
A-II, B-I, C-IV, D-III
D
A-III, B-IV, C-I, D-II
40
Given below are two statements: Statement I: The oxidation state of carbon in HCOOH is +2. Statement II: The oxidation state of nitrogen in N3H is –1/3. In the light of the above statements, choose the most appropriate answer:
A
Both Statement I and Statement II are correct.
B
Statement I is correct but Statement II is incorrect.
C
Statement I is incorrect but Statement II is correct.
D
Both Statement I and Statement II are incorrect.
41
A metal X displaces nickel from nickel sulphate solution but does not displace manganese from manganese sulphate solution. What is the correct order of their reducing powers?
A
Ni > Mn > X
B
X > Mn > Ni
C
Mn > X > Ni
D
Mn > Ni > X
42
Identify which of the following species cannot act as reducing agent?
A
NO2
B
ClO2
C
CO2
D
SO2
43
Consider the following reaction:
The values of x, y and z in the balanced chemical reaction are respectively;
A
2, 5 and 16
B
5, 2 and 8
C
5, 2 and 16
D
2, 5 and 8
44
The equivalent weight of Fe^3+ (Molar mass = M g/mol) in the given reaction is: Fe^3+ + e− → Fe^2+
A
M/3
B
M/2
C
M/4
D
M
45
Given below are two statements: Statement I: Oxidation state of central Br in Br3O8 is +4. Statement II: Oxidation state of terminal Br in Br3O8 is +6. Choose the correct answer:
A
Both Statement I and Statement II are correct.
B
Statement I is correct but Statement II is incorrect.
C
Statement I is incorrect but Statement II is correct.
D
Both Statement I and Statement II are incorrect.
46
The oxidation number of phosphorus varies from;
A
–3 to +5
B
–1 to +1
C
–3 to +3
D
–5 to +1
47
The change in oxidation state of sulphur in the given reaction is from: PbS + 4H2O2 → PbSO4 + 4H2O
A
+2 to +6
B
–2 to +6
C
–2 to +4
D
+2 to +4
48
Given below are two statements: Statements I: In Br3O8 each of the two terminal bromine atoms are present in +6 oxidation state. Statements II: In Br3O8, the middle bromine is present in +4 oxidation state.
A
Statement I is correct but Statement II is incorrect.
B
Statement I is incorrect but Statement II is correct.
C
Both Statement I and Statement II are correct.
D
Both Statement I and Statement II are incorrect.
49
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R): Assertion (A) : Oxidation involves gain of electrons and reduction involves loss of electrons. Reason (R): The overall reaction in which oxidation and reduction occur simultaneously, is called redox reaction.
A
A is true but R is false.
B
A is false but R is true.
C
Both A and R are true and R is the correct explanation of A.
D
Both A and R are true but R is NOT the correct explanation of A.
50
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R): Assertion (A): MnO2 can act as an oxidizing agent as well as reducing agent. Reason (R): Oxidation state of Mn in MnO2 lies between its highest (+7) and lowest (zero) oxidation state.
A
A is true but R is false.
B
A is false but R is true.
C
Both A and R are true and R is the correct explanation of A.
D
Both A and R are true but R is NOT the correct explanation of A.
51
Oxidation state of middle carbon in C3O2 (Carbon suboxide) is;
A
+1
B
+2
C
zero
D
+4/3
52
Consider the balanced reaction:
The correct coefficient x, y and z are:
A
x = 4, y = 3, z = 2
B
x = 2, y = 3, z = 5
C
x = 3, y = 4, z = 6
D
x = 2, y = 6, z = 4
53
Match List-I with List-II. List-I (Chemical Species) List-II (Oxidation no. of central atom) A. CrO5 B. I3− C. O3 D. F−
A
A-I, B-II, C-III, D-IV
B
A-III, B-IV, C-I, D-II
C
A-II, B-III, C-I, D-IV
D
A-I, B-II, C-IV, D-III
54
Standard reduction potentials of the half reactions are given below: F2(g) + 2e− → 2F− (aq); E° = +2.85V Cl2(g) + 2e− → 2Cl− (aq); E° = +1.36V Br2(l) + 2e− → 2Br− (aq); E° = +1.06V I2(s) + 2e− → 2I− (aq); E° = +0.53V The strongest oxidizing agent is;
A
F2
B
Br2
C
Cl2
D
I2
55
Cl2 changes to Cl− and ClO− in cold and dil. NaOH. The equivalent weight of Cl2 (molar mass = M) will be:
A
M
B
M/2
C
M/3
D
2M/3
56
In the reaction: Br2 + 6CO3^2− + 3H2O → 5Br− + BrO3− + 6HCO3−
A
Bromine is oxidized and carbonate is reduced.
B
Bromine is oxidized and water is reduced.
C
Bromine is both oxidized and reduced.
D
Bromine is neither oxidized nor reduced.
57
In which of the following reactions H2O2 acts as a reducing agent?
A
H2O2 + 2H+ + 2e− → 2H2O
B
H2O2 → O2 + 2H+ + 2e−
C
H2O2 + 2e− → 2OH−
D
H2O2 + 2OH− → O2 + 2H2O + 2e−
58
Reduction is a process which involves;
A
electronation.
B
addition of hydrogen or removal of oxygen.
C
addition of metal or removal of non-metal
D
All of these
59
In ionic equation, BiO3− + 6H+ + xe− → Bi3+ + 3H2O the value of x is;
A
6
B
2
C
4
D
3
60
In C + H2O → CO + H2 ; H2O acts as:
A
Oxidant
B
Reductant
C
Bleaching agent
D
Substance oxidised
61
The oxidation number of phosphorus varies from;
A
–3 to +5
B
–1 to +1
C
–3 to +3
D
–5 to +1
62
Consider the following statements: (I) Addition of oxygen or electronegative element to a substance is called oxidation. (II) Electron donors act as reducing agent. (III) An oxidising agent accepts electrons. The correct statements are;
A
I and II only
B
I and III only
C
II and III only
D
I, II and III
63
The average oxidation state of Fe in Fe3O4 is:
A
+4/3
B
+8/3
C
+2/3
D
+5/3
64
In the reaction, H2S + H2O2 → S + 2H2O; (A) S is the oxidant. (B) H2O is the reductant (C) H2S is an oxidant and H2O2 is a reductant. (D) H2S is a reductant and H2O2 is an oxidant. The correct statement is;
A
A only
B
B only
C
C only
D
D only
65
For the reaction, MnO4− + I− → MnO2 + I2 in basic medium, coefficients of I− and MnO4− in the balanced equation respectively are;
A
6, 2
B
2, 6
C
1, 6
D
2, 1
66
Given; Co3+ + e− → Co2+ ; E° = +1.81V Pb4+ + 2e− → Pb2+ ; E° = +1.67V Ce4+ + e− → Ce3+ ; E° = +1.61V Oxidizing power of the species will increase in the order:
A
Pb4+ < Ce4+ < Co3+
B
Co3+ < Pb4+ < Ce4+
C
Co3+ < Ce4+ < Pb4+
D
Ce4+ < Pb4+ < Co3+
67
In which of the following compounds, oxygen shows positive oxidation state?
A
O2F2
B
RbO2
C
H2O2
D
CO2
68
Which of the following does not behave as reducing agent? A. H2SO3 B. SO2 C. H2S D. HNO3 The correct options is/are;
A
A only
B
D only
C
A and B
D
C and D
69
Consider the following reaction; S + 12OH− → 4S^2− + 2S2O3^2− + 8H2O Which of the following is correct for the above reaction?
A
Sulphur is only oxidised.
B
Sulphur is only reduced.
C
Sulphur is neither oxidised nor reduced.
D
It is a disproportionation reaction.
70
When a zinc rod is kept in a copper nitrate solution what happens?
A
Zinc is deposited on copper.
B
Copper is deposited on zinc.
C
The solution turns blue to green.
D
The solution turns blue to pink.
71
For the reaction given below, which statement is correct? 2Fe + 3CdCl2 → 2FeCl3 + 3Cd
A
Fe is the oxidizing agent.
B
Cd undergoes oxidation.
C
Cd is the reducing agent.
D
Fe undergoes oxidation.
72
Which of the following is a redox reaction?
A
K2SO4 + BaCl2 → BaSO4 + 2KCl
B
BaO + H2SO4 → BaSO4 + H2O
C
AgNO3 + NaCl → AgCl + NaNO3
D
2H2S + SO2 → 2H2O + 3S
73
Which of the following is not a redox reaction?
A
CuSO4 + Zn → Cu + ZnSO4
B
CaCO3 → CaO + CO2
C
2Na + 2H2O → 2NaOH + H2
D
Cl2 + 2Br− → 2Cl− + Br2
74
The number of oxygen atoms showing –1 oxidation state in CrO5 molecule are:
A
Five
B
Four
C
Two
D
Three
75
In the reaction: Ag + H2SO4 → Ag2SO4 + H2O + SO2 Sulphuric acid acts as;
A
Oxidising agent
B
Reducing agent
C
Catalyst
D
None of these
76
Chlorine has +1 oxidation state in;
A
HCl
B
HClO4
C
ICl
D
Cl2O
77
The number of moles of KMnO4 that will be needed to react completely with one mole of ferrous oxalate in acid solution is
A
3/5
B
2/5
C
4/5
D
1
78
CuSO4 + Zn → Cu + ZnSO4 is an example of;
A
Combination reaction
B
Decomposition reaction
C
Metal displacement reaction
D
Non-metal displacement reaction
79
The oxidising agent in the following reaction is: S2O3^2− + I2 → S4O6^2− + 2I−
A
I2
B
S2O3^2−
C
I−
D
Both (1) and (3)
80
2Na2O2 → 2Na2O + O2, is an example of disproportionation because:
A
Oxidation number of oxygen only decreases
B
Oxidation number of oxygen only increases
C
Oxidation number of oxygen decreases as well as increases
D
Oxidation number of oxygen neither decreases nor increases
81
In all of its compounds, oxidation state of oxygen may vary from;
A
+6 to –6
B
–2 to +2
C
+2 to +6
D
0 to –2
82
In the ionic equation:
the n-factor of KBrO3 will be;
A
5
B
2
C
6
D
4
83
Identify the species undergoing oxidation in the given reaction; H2S(g) + Cl2(g) → 2HCl(g) + S(g)
A
Cl2
B
H2S
C
HCl
D
S
84
Which of the following represents a correctly balanced half reaction?
A
Cl2 + 2e− → 2Cl−
B
Fe → Fe2+ + 2e−
C
O2 + 4e− → 2O2−
D
2H+ + 2e− → H2
85
Oxidation state of P in PO4^3− is;
A
+4
B
+3
C
+5
D
+2
86
The oxidation state of two terminal and two middle sulphur atoms in respectively are:
A
+4 and zero
B
+5 and zero
C
+2.5 and +2.5
D
+2 and +3
87
Given below are two statements: Statements I: KMnO4 can work both as an oxidising as well as reducing agent. Statements II: The equation, Mg(s) + CuO(s) → MgO(s) + Cu(s) represents decomposition reaction.
A
Statement I is correct but Statement II is incorrect.
B
Statement I is incorrect but Statement II is correct.
C
Both Statement I and Statement II are correct.
D
Both Statement I and Statement II are incorrect.
88
In the reaction
What is the value of n?
A
7
B
2
C
3
D
5
89
In which of the following compounds the oxidation number of carbon is maximum?
A
HCHO
B
CHCl3
C
CH3OH
D
C12H22O11
90
Oxidation number of an element in its free state is;
A
positive
B
zero
C
negative
D
fractional
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