Redox and Electrochemistry Test

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Redox and Electrochemistry Test - 4

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Weekly Quiz Competition

Question 1
1 / -0

An ideal battery does not have which property

A
should be light in weight

B
be compact

C
voltage variation during the use

D
should have longer life

Solution

An ideal battery should have following desirable characters. It should be reasonably light, compact. Its voltage should not vary much during its life i.e., period of use.
Question 2
1 / -0

Secondary cells are:

A
repeated action cell

B
dry cell

C
mercury cell

D
Leclanche cell

Solution

The cell in which original reactants are regenerated by passing direct current from external source, i.e., it is re-charged, is called secondary cell.
Dry cell is compact form of leclanche cell which is primary cell.
Question 3
1 / -0

Which of the following does not increase with dilution?

A
Conductance

B
Specific conductance

C
Molar conductance

D
None of the above

Solution

Specific conductance decreases with dilution, while conductance and molar conductance will increase with dilusion; because upon the number of ions per unit volume will decrease.
Question 4
1 / -0

When 1M NaI is electrolyzed, bubbles of gas from one electrode and a reddish brown substance forms on the other. The half reaction at the cathode is

A
2I^- → I₂ + 2e^-

B
Na⁺ + e^-→ Na

C
H₂O → 1/2 O₂ + 2H⁺ + 2e^-

D
2H₂O + 2e^-→ H₂ + 2OH^-

Solution

Possible cathode half-reactions (reduction):

1) Reduction of H₂O:

2H₂O(l) + 2e^-→ H₂(g) + 2OH^- E = -0.42 V

→ with overvoltage E ≈ -1.0 V

2) Reduction of cation in the solution:

Na⁺ + e^-→ Na(s) E = -2.71 V

→ Half-reaction (1) has the highest (most positive) E value

Therefore, half cell reaction at cathode is: 2H₂O(l) + 2e^-→ H₂(g) + 2OH^-
Question 5
1 / -0

The cell Pt|H₂(g) (1atm)|H⁺; pH = x|| Normal electrode has EMF of 0.64 volt at 25 °C. The standard reduction potential of normal electrode is 0.28 V. The anodic compartment has PH? Take 2.303RT/F ^{= 0.06} at 298 K.

A
4

B
5

C
6

D
None of these

Solution

Anode

H₂ →2H⁺ + 2e^-

Cathode

2H⁺ + 2e^-→H₂

E_cell = E_calomel + 0.06 PH

0.64 = 0.28 + 0.06PH

PH = 6

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Re-Attempt Weekly Quiz Competition

Redox and Electrochemistry Test - 4

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Redox and Electrochemistry Test - 4

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Question 1

should be light in weight

be compact

voltage variation during the use

should have longer life

Solution

Question 2

repeated action cell

dry cell

mercury cell

Leclanche cell

Solution

Question 3

Conductance

Specific conductance

Molar conductance

None of the above

Solution

Question 4

2I- → I2 + 2e-

Na+ + e-→ Na

H2O → 1/2 O2 + 2H+ + 2e-

2H2O + 2e-→ H2 + 2OH-

Solution

Question 5

4

5

6

None of these

Solution

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2I^- → I₂ + 2e^-

Na⁺ + e^-→ Na

H₂O → 1/2 O₂ + 2H⁺ + 2e^-

2H₂O + 2e^-→ H₂ + 2OH^-