Reduction worksheet





In terms of chemistry, Reduction means the process of adding hydrogen or removing oxygen from a compound in a chemical reaction.

In this article you can find some question related to oxidation and reduction with their answers.

Questions:

1. Chlorine is in +1 oxidation state in
(a)    HCl

(b)   HClO_4

(c)    ICl

(d)   Cl_2O

 

2.  In which of the following reactions there is no change in valency?

(a)    4KClO_3 \to 3KClO_4 + KCl

(b)   HBr + AgNo_3 \to AgBr + HNO_3

(c)    H_2 + Br_2 \to 2HBr

(d)   BaO + O_2 \to 2BaO_2

 

3. Which of the following reaction involves oxidation and reduction?

(a)    NaBr + HCl \to NaCl + HBr

(b)   HBr + AgNO_3 \to AgBr + HNO_3

(c)    H_2 + Br_2 \to HBr

(d)   Na_2O + H_2SO_4 \to Na_2SO_4 + H_2O

 

4. In which of the following reactions, has underlined substance been reduced?

(a)    CO + \underset{-}{CuO} \to CO_2 +Cu

(b)   \underset{-}{Cu}O + 2HCl \to CuCl_2 + H_2O

(c)    \text{steam} + \text{iron} \to H_2 + \text{iron oxide}

(d)   hydrogen + iron oxide = water + iron

 

5. The most common oxidation state of an element is -2. The number of electrons present in its outermost sheel is:

(a)    2

(b)   4

(c)    6

(d)   8

 

6. Oxidation of thiosulphate ion by iodine gives

(a)    SO_3^=

(b)   SO_4^=

(c)    S_4O_6^=

(d)   S_2O_3^=

 

7. The oxidation state of nitrogen in N_3His:

(a)    +1/2

(b)   +3

(c)    -1

(d)   -1/3

 

8. The oxidation number and valency of sulphur in the sulphur molecule (S_3) are respectively:

(a)    0 and 2

(b)   6 and 8

(c)    0 and 8

(d)   6 and 2

 

9. Oxidation state of oxygen atom in potassium peroxide is:

(a)    Zero

(b)   -1/2

(c)    -1

(d)   -2

 

10. In which of the following compounds transition metal is in oxidation state zero?

(a)    [CO(NH_3)_6]Cl_2

(b)   [Fe(H_2O)_5SO_4

(c)    Ni(CO)_4

(d)   [Fe(H_2O)_3](OH)_2

 

11. In which one of the following changes there are transfer of five electrons?

(a)    MnO^-_4 \to Mn^{++}

(b)   CrO^{2-}_4 \to Cr^{3+}

(c)    MnO^{2-}_4 \to MnO_2

(d)   Cr_2O^{2-}_7 \to 2Cr^{3+}

 

12. The oxidation number of nitrogen in NH_2OH  is

(a)    +1

(b)   -1

(c)    -3

(d)   -2

 

13. In which of the following reaction is hydrogen peroxide a reducing agent?

(a)    2FeCl_2 + 2HCl + H_2O_2 \to 2FeCl_2 + 2H_2O

(b)   Cl_2 + H_2O_2 \to 2HCl + O_2

(c)    2HI + H_2O_2 \to 2H_2O + I_2

(d)   H_2SO_3 + H_2O_2 \to H_2SO_4 + H_2O

 

14. The process in which oxidation number increases is known as:

(a)    Oxidation

(b)   Reduction

(c)    auto oxidation

(d)   none of the above

 

15. The oxidation states of phosphorous vary from:

(a)    -3 to +5

(b)   -1 to +1

(c)    -3 to +3

(d)   -5 to + 1

 

16. In the reaction,

Cr_2O^{2-}_7 + 14H^+ + 6I^- \to 2Cr^{3+} + 3H_2O +3I_2 Which element is reduced?

(a)    Cr

(b)   H

(c)    O

(d)   I

 

17. In which of the following reaction, there is no change in valency?

(a)    SO_2 + 2H_2S \to 2H_2O + 3S

(b)   2Na + O_2 \to Na_2O_2

(c)    Na_2O_2 + H_2SO_4 \to Na_2SO_4 + H_2O_2

(d)   4KClO_3 \to 3KClO_4 + KCl

 

18. The compound that can work both as oxidizing and reducing agent is:

(a)    KMnO_4

(b)   H_2O_2

(c)    BaO_2

(d)   K_2Cr_2O_7

 

19. In the reaction,

Cl_2 + OH^- \to Cl^- + ClO^-_3 + H_2O Chlorine is:

(a)    Oxidized

(b)   Reduced

(c)    oxidized as well as reduced

(d)   neither oxidized not reduced

 

20. Oxidation number of P in KH_2PO2 is:

(a)    +1

(b)   +3

(c)    +5

(d)   -3

 

21. The anhydride of hypochlorous acid is:

(a)    ClO_3

(b)   ClO_3

(c)    Cl_2O_5

(d)   Cl_2O

 

22. In the presence of dilute H_2SO_4, the equivalent weight of KMnO_4 is:

(a)    1 / 5 of its molecular weight

(b)   1/6 of its molecular weight

(c)    1 / 10 of its molecular weight

(d)   1 / 2 of its molecular weight

 

23. The strongest reducing agent is:

(a)    HNO_2

(b)   H_2S

(c)    H_2SO_3

(d)   SnCl_2

 

24. In the reaction,

2KI + Br_2 \to 2KBr + I_2 The oxidizing agent is:

(a)    KI

(b)   Br_2

(c)    KBr

(d)   none of these

 

25. In the reaction,

2FeCl_2 + Cl_2 \to 2FeCl_3 the equivalent weight of FeCl_2 will be

(a)    equal to its molecular weight

(b)   half of its molecular weight

(c)    1 / 3 rd of its molecular weight

(d)   1/6th  of its molecular weight

 

Answers:

1.(d)       2. (b)        3. (c)       4. (a)        5. (c)

6. (c)      7. (d)        8. (a)       9. (b)        10. (c)

11. (a)     12. (b)     13. (b)      14. (a)      15. (a)

16. (a)    17. (c)     18. (b)      19. (c)      20. (a)

21. (d)     22. (a)    23. (b)     24. (b)     25. (a)



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