Redox Reactions Practice Questions - DPP for JEE

 Page 1


PART-I (Single Correct MCQs)
1. Which of the following is a redox reaction?
(a) NaCl + KNO
3
 NaNO
3
 + KCl
(b) CaC
2
O
4
 + 2HCl CaCl
2 
+ H
2
C
2
O
4
(c) Mg(OH)
2
 + 2NH
4
Cl MgCl
2
 + 2NH
4
OH
(d) Zn + 2AgCN  2Ag + Zn(CN)
2
.
2. Several blocks of magnesium are fixed to the bottom of a ship to
(a) make the ship lighter
(b) prevent action of water and salt
(c) prevent puncturing by under-sea rocks
(d) keep away the sharks
3. Which of the following chemical reactions depict the oxidizing
beahviour of H
2
SO
4
?
(a)
Page 2


PART-I (Single Correct MCQs)
1. Which of the following is a redox reaction?
(a) NaCl + KNO
3
 NaNO
3
 + KCl
(b) CaC
2
O
4
 + 2HCl CaCl
2 
+ H
2
C
2
O
4
(c) Mg(OH)
2
 + 2NH
4
Cl MgCl
2
 + 2NH
4
OH
(d) Zn + 2AgCN  2Ag + Zn(CN)
2
.
2. Several blocks of magnesium are fixed to the bottom of a ship to
(a) make the ship lighter
(b) prevent action of water and salt
(c) prevent puncturing by under-sea rocks
(d) keep away the sharks
3. Which of the following chemical reactions depict the oxidizing
beahviour of H
2
SO
4
?
(a)
(b) 
(c)
(d)
4. Which of the following statements are correct concerning redox
properties?
(i) A metal M for which E° for the half life reaction M
n+
 + ne
–
  M is
very negative will be a good reducing agent.
(ii) The oxidizing power of the halogens decreases from chlorine to iodine.
(iii) The reducing power of hydrogen halides increases from hydrogen
chloride to hydrogen iodide
(a) (i), (ii) and (iii)
(b) (i) and (ii)
(c) (i) only
(d) (ii) and (iii)
5. Arrange the following in the order of their decreasing electrode
potentials : Mg, K, Ba and Ca
(a) K, Ca, Ba, Mg
(b) Ba, Ca, K, Mg
(c) Ca, Mg, K, Ba
(d) Mg, Ca, Ba, K
6. Given :
XNa
2
HAsO
3 
+ YNaBrO
3
 +  ZHCl  NaBr + H
3
AsO
4
 + NaCl
The values of X, Y and Z in the above redox reaction are respectively :
(a) 2, 1, 2
(b) 2, 1, 3
(c) 3, 1, 6
(d) 3, 1, 4
7. Oxidation state of sulphur in anions  and 
Page 3


PART-I (Single Correct MCQs)
1. Which of the following is a redox reaction?
(a) NaCl + KNO
3
 NaNO
3
 + KCl
(b) CaC
2
O
4
 + 2HCl CaCl
2 
+ H
2
C
2
O
4
(c) Mg(OH)
2
 + 2NH
4
Cl MgCl
2
 + 2NH
4
OH
(d) Zn + 2AgCN  2Ag + Zn(CN)
2
.
2. Several blocks of magnesium are fixed to the bottom of a ship to
(a) make the ship lighter
(b) prevent action of water and salt
(c) prevent puncturing by under-sea rocks
(d) keep away the sharks
3. Which of the following chemical reactions depict the oxidizing
beahviour of H
2
SO
4
?
(a)
(b) 
(c)
(d)
4. Which of the following statements are correct concerning redox
properties?
(i) A metal M for which E° for the half life reaction M
n+
 + ne
–
  M is
very negative will be a good reducing agent.
(ii) The oxidizing power of the halogens decreases from chlorine to iodine.
(iii) The reducing power of hydrogen halides increases from hydrogen
chloride to hydrogen iodide
(a) (i), (ii) and (iii)
(b) (i) and (ii)
(c) (i) only
(d) (ii) and (iii)
5. Arrange the following in the order of their decreasing electrode
potentials : Mg, K, Ba and Ca
(a) K, Ca, Ba, Mg
(b) Ba, Ca, K, Mg
(c) Ca, Mg, K, Ba
(d) Mg, Ca, Ba, K
6. Given :
XNa
2
HAsO
3 
+ YNaBrO
3
 +  ZHCl  NaBr + H
3
AsO
4
 + NaCl
The values of X, Y and Z in the above redox reaction are respectively :
(a) 2, 1, 2
(b) 2, 1, 3
(c) 3, 1, 6
(d) 3, 1, 4
7. Oxidation state of sulphur in anions  and 
increases in the orders :
(a)
(b)
(c)
(d)
8. Amongst the following, identify the species with an atom in + 6
oxidation state:
(a) [MnO
4
]
–
(b) [Cr(CN)
6
]
3–
(c) Cr
2
O
3
(d) CrO
2
Cl
2
9. Which one of the following cannot function as an oxidising agent ?
(a) I
–
(b) S(s)
(c)
(d)
10. In the standardization of Na
2
S
2
O
3
 using K
2
Cr
2
O
7
 by iodometry, the
equivalent weight of K
2
Cr
2
O
7
 is
 (a) (molecular weight)/2
(b) (molecular weight)/6
(c) (molecular weight)/3
(d) same as molecular weight
11. Consider the reaction:
Which of the following statements is correct?
Page 4


PART-I (Single Correct MCQs)
1. Which of the following is a redox reaction?
(a) NaCl + KNO
3
 NaNO
3
 + KCl
(b) CaC
2
O
4
 + 2HCl CaCl
2 
+ H
2
C
2
O
4
(c) Mg(OH)
2
 + 2NH
4
Cl MgCl
2
 + 2NH
4
OH
(d) Zn + 2AgCN  2Ag + Zn(CN)
2
.
2. Several blocks of magnesium are fixed to the bottom of a ship to
(a) make the ship lighter
(b) prevent action of water and salt
(c) prevent puncturing by under-sea rocks
(d) keep away the sharks
3. Which of the following chemical reactions depict the oxidizing
beahviour of H
2
SO
4
?
(a)
(b) 
(c)
(d)
4. Which of the following statements are correct concerning redox
properties?
(i) A metal M for which E° for the half life reaction M
n+
 + ne
–
  M is
very negative will be a good reducing agent.
(ii) The oxidizing power of the halogens decreases from chlorine to iodine.
(iii) The reducing power of hydrogen halides increases from hydrogen
chloride to hydrogen iodide
(a) (i), (ii) and (iii)
(b) (i) and (ii)
(c) (i) only
(d) (ii) and (iii)
5. Arrange the following in the order of their decreasing electrode
potentials : Mg, K, Ba and Ca
(a) K, Ca, Ba, Mg
(b) Ba, Ca, K, Mg
(c) Ca, Mg, K, Ba
(d) Mg, Ca, Ba, K
6. Given :
XNa
2
HAsO
3 
+ YNaBrO
3
 +  ZHCl  NaBr + H
3
AsO
4
 + NaCl
The values of X, Y and Z in the above redox reaction are respectively :
(a) 2, 1, 2
(b) 2, 1, 3
(c) 3, 1, 6
(d) 3, 1, 4
7. Oxidation state of sulphur in anions  and 
increases in the orders :
(a)
(b)
(c)
(d)
8. Amongst the following, identify the species with an atom in + 6
oxidation state:
(a) [MnO
4
]
–
(b) [Cr(CN)
6
]
3–
(c) Cr
2
O
3
(d) CrO
2
Cl
2
9. Which one of the following cannot function as an oxidising agent ?
(a) I
–
(b) S(s)
(c)
(d)
10. In the standardization of Na
2
S
2
O
3
 using K
2
Cr
2
O
7
 by iodometry, the
equivalent weight of K
2
Cr
2
O
7
 is
 (a) (molecular weight)/2
(b) (molecular weight)/6
(c) (molecular weight)/3
(d) same as molecular weight
11. Consider the reaction:
Which of the following statements is correct?
(a) Sn
4+
 is the oxidizing agent because it undergoes oxidation
(b) Sn
4+
 is the reducing agent because it undergoes oxidation
(c) H
2
SO
3
 is the reducing agent because it undergoes oxidation
(d) H
2
SO
3
 is the reducing agent because it undergoes reduction
12. The species that undergoes disproportionation in an alkaline medium
are
(a) Cl
2
(b)
(c) NO
2
(d) All of these
13. H
2
S
 
acts only as a reducing agent while SO
2
 can act
 
both as a reducing
and oxidizing  agent because
(a) oxygen is more – ve in SO
2
(b) hydrogen in H
2
S is more  + ve than oxygen
(c) S in SO
2
 has one oxidation state
(d) S in H
2
S has – 2 oxidation state
14. Which substance serves as reducing agent in the following reaction
?
14H
+
 + Cr
2
 + 3Ni  2Cr
3+
 + 7H
2
O + 3Ni
2+
(a) H
2
O
(b) Ni
(c) H
+
(d) Cr
2
15. Which one of the following reactions involves disproportionation?
(a) 2H
2
SO
4
 + Cu ? CuSO
4
 + 2H
2
O + SO
2
(b) As
2
O
3
 + 3H
2
S ? As
2
S
3
 + 3H
2
O
(c) 2KOH + Cl
2
 ? KCl + KOCl + H
2
O
(d) Ca
3
P
2
 + 6H
2
O ? 3Ca(OH)
2
 + 2PH
3
16. Point out the correct statement of the following about Na
2
S
4
O
6
.
(a) Average oxidation number of S atom is +2
Page 5


PART-I (Single Correct MCQs)
1. Which of the following is a redox reaction?
(a) NaCl + KNO
3
 NaNO
3
 + KCl
(b) CaC
2
O
4
 + 2HCl CaCl
2 
+ H
2
C
2
O
4
(c) Mg(OH)
2
 + 2NH
4
Cl MgCl
2
 + 2NH
4
OH
(d) Zn + 2AgCN  2Ag + Zn(CN)
2
.
2. Several blocks of magnesium are fixed to the bottom of a ship to
(a) make the ship lighter
(b) prevent action of water and salt
(c) prevent puncturing by under-sea rocks
(d) keep away the sharks
3. Which of the following chemical reactions depict the oxidizing
beahviour of H
2
SO
4
?
(a)
(b) 
(c)
(d)
4. Which of the following statements are correct concerning redox
properties?
(i) A metal M for which E° for the half life reaction M
n+
 + ne
–
  M is
very negative will be a good reducing agent.
(ii) The oxidizing power of the halogens decreases from chlorine to iodine.
(iii) The reducing power of hydrogen halides increases from hydrogen
chloride to hydrogen iodide
(a) (i), (ii) and (iii)
(b) (i) and (ii)
(c) (i) only
(d) (ii) and (iii)
5. Arrange the following in the order of their decreasing electrode
potentials : Mg, K, Ba and Ca
(a) K, Ca, Ba, Mg
(b) Ba, Ca, K, Mg
(c) Ca, Mg, K, Ba
(d) Mg, Ca, Ba, K
6. Given :
XNa
2
HAsO
3 
+ YNaBrO
3
 +  ZHCl  NaBr + H
3
AsO
4
 + NaCl
The values of X, Y and Z in the above redox reaction are respectively :
(a) 2, 1, 2
(b) 2, 1, 3
(c) 3, 1, 6
(d) 3, 1, 4
7. Oxidation state of sulphur in anions  and 
increases in the orders :
(a)
(b)
(c)
(d)
8. Amongst the following, identify the species with an atom in + 6
oxidation state:
(a) [MnO
4
]
–
(b) [Cr(CN)
6
]
3–
(c) Cr
2
O
3
(d) CrO
2
Cl
2
9. Which one of the following cannot function as an oxidising agent ?
(a) I
–
(b) S(s)
(c)
(d)
10. In the standardization of Na
2
S
2
O
3
 using K
2
Cr
2
O
7
 by iodometry, the
equivalent weight of K
2
Cr
2
O
7
 is
 (a) (molecular weight)/2
(b) (molecular weight)/6
(c) (molecular weight)/3
(d) same as molecular weight
11. Consider the reaction:
Which of the following statements is correct?
(a) Sn
4+
 is the oxidizing agent because it undergoes oxidation
(b) Sn
4+
 is the reducing agent because it undergoes oxidation
(c) H
2
SO
3
 is the reducing agent because it undergoes oxidation
(d) H
2
SO
3
 is the reducing agent because it undergoes reduction
12. The species that undergoes disproportionation in an alkaline medium
are
(a) Cl
2
(b)
(c) NO
2
(d) All of these
13. H
2
S
 
acts only as a reducing agent while SO
2
 can act
 
both as a reducing
and oxidizing  agent because
(a) oxygen is more – ve in SO
2
(b) hydrogen in H
2
S is more  + ve than oxygen
(c) S in SO
2
 has one oxidation state
(d) S in H
2
S has – 2 oxidation state
14. Which substance serves as reducing agent in the following reaction
?
14H
+
 + Cr
2
 + 3Ni  2Cr
3+
 + 7H
2
O + 3Ni
2+
(a) H
2
O
(b) Ni
(c) H
+
(d) Cr
2
15. Which one of the following reactions involves disproportionation?
(a) 2H
2
SO
4
 + Cu ? CuSO
4
 + 2H
2
O + SO
2
(b) As
2
O
3
 + 3H
2
S ? As
2
S
3
 + 3H
2
O
(c) 2KOH + Cl
2
 ? KCl + KOCl + H
2
O
(d) Ca
3
P
2
 + 6H
2
O ? 3Ca(OH)
2
 + 2PH
3
16. Point out the correct statement of the following about Na
2
S
4
O
6
.
(a) Average oxidation number of S atom is +2
(b) Oxidation number of two S atoms is zero each and that of other two is +5
each
(c) Oxidation number of two S atoms is +1 each and that of other two is +4
each
(d) None of these
17. Thiosulphate reacts differently with iodine and bromine in the reactions
given below.
Which of the following statements justifies the above dual behaviour of
thiosulphate?
(a) Bromine is a stronger oxidant than iodine
(b) Bromine is a weaker oxidant than iodine
(c) Thiosulphate undergoes oxidation by bromine and reduction by iodine in
these reactions
(d) Bromine undergoes oxidation and iodine undergoes reduction in these
reactions
18. Standard reduction potentials of the half reactions are given below :
F
2
(g) + 2e
–
 ? 2F
– 
(aq);  E° = + 2.85 V
Cl
2
(g) + 2e
–
 ? 2Cl
–
(aq);  E° = + 1.36 V 
Br
2
(l) + 2e
–
 ? 2Br
–
(aq);  E° = + 1.06 V
I
2
(s) + 2e
–
 ? 2I
–
(aq); E° = + 0.53 V
The strongest oxidising and reducing agents respectively are :
(a) F
2
 and I
–
(b) Br
2
 and Cl
–
(c) Cl
2
 and Br
–
(d) Cl
2
 and I
2
19. A mixture of potassium chlorate, oxalic acid and sulphuric acid is
heated. During the reaction which element undergoes maximum change