Class XII Chemistry Redox and Electrochemistry 5

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Question 1

25 ml of a 0.1 (M) solution of a stable cation of transition metal z reacts exactly with 25 ml of 0.04 (M) acidified KMnO₄ solution. Which of the following is most likely to represent the change in oxidation state of z correctly ?

• AZ⁺→ Z²⁺
• BZ²⁺→ Z³⁺
• CZ³⁺→ Z⁴⁺
• DZ²⁺→ Z⁴⁺

Question 2

In which of the following complexes the transition metal has ZERO oxidation state.

• A[Fe(CO)₅]
• B[Fe(CN)₆]^3-
• C[Ti(H₂O)₆]³⁺
• D[Fe(CN)₆ ]^4-

Question 3

In electrolysis of an aqueous solution of sodium sulphate, 2.4L of oxygen at STP was liberated at anode. The volume of hydrogen at STP liberated at cathode would be

• A1.2L
• B2.4L
• C2.6L
• D4.8L

Question 4

The current of 9.65 A is passed for 3hrs between nickel electrods in 0.5L of a 2 × 10^–3 M solution of Ni(NO₃)₂, the molarity of solution after electrolysis would be

• A0.46 M
• B0.625 M
• C2× 10^–3 M
• D1.25 M

Question 5

How many coulombs are required for the reduction of one mole of HNO₃ to NO?

• A3.86 x10⁵ C
• B1.93 x10⁵ C
• C9.65 x10⁴ C
• D2.89 x10⁵ C

Question 6

Refining of impure copper with zinc impurity is to be done by electrolysis using electrodes as:

• AA
• BB
• CC
• DD

Question 7

Hydrogen electrode is dipped in a solution of pH 5 at 25 °C; The potential of the cell is

• A0.295V
• B-0.295V
• C0.59V
• D-0.59V

Question 8

For cell reaction having 3 electron change, the standard EMF of the cell was found to be 0.295V at 25 °C. The equilibrium constant for this reaction is

• A2.95 x10¹⁵
• B10
• C1 x10¹⁵
• D1 x10^-15

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