Electrochemistry Test

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Electrochemistry Test - 5

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Weekly Quiz Competition

Question 1
1 / -0

A sample of 1.08 g of pure silver was converted into silver nitrate and its solution was taken in a beaker. It was electrolysed using platinum cathode and silver anode. 0.01 faraday of electric current was passed using 0.15 volt above the decomposition potential of silver. The silver content of the beaker after the above process must be

A
zero

B
0.108 g

C
10.8 g

D
1.08 g
Question 2
1 / -0

Conductivity always decreases with decrease in concentration both, for weak and strong electrolytes because of the fact that

A
mobility of ions that carry the current in a solution increases on dilution

B
the number of ions per unit volume that carry the current in a solution decreases on dilution

C
the number of collisions of ions per unit volume that carry the current in a solution increases on dilution

D
the number of ions per unit volume that carry the current in a solution increases on dilution

Solution

Conductivity is conductance of one centimetercube of the solution. so on dilution the number of ions per cm3 decreases.
Question 3
1 / -0

During the measurement of EMF of a half cell using a reference electrode and a salt bridge, if the salt bridge is removed, then the voltage

A
remains unchanged

B
decreases to half the previous value

C
increases to its maximum value

D
drops to zero or becomes negative
Question 4
1 / -0

Molar conductivity denoted by the symbol Λm is related to the conductivity of the solution by the equation (κ is the conductivity and c the concentration)

A
Λm=2/kc

B
Λm=k/c

C
Λm=c/k

D
Λm=k/c

Solution

Molar conductivity is conducting power of all the ions produced by dissolving 1 mole of electrolyte in solution.
Question 5
1 / -0

Directions: The following question consists of Assertion (A) and Reason (R). Mark the appropriate answer.

(A): Equivalent conductance of all electrolytes decreases with increasing concentration.
(R): Lesser ions are available per gram equivalent at higher concentration.

A
Both (A) and (R) are correct and (R) is the right explanation of (A).

B
Both (A) and (R) are correct, but (R) is not the right explanation of (A).

C
(A) is correct, but (R) is incorrect.

D
(A) is incorrect, but (R) is correct.
Question 6
1 / -0

standard hydrogen electrode operated under standard conditions of 1 atm H2 pressure, 298K, and pH = 0 has a cell potential of

A
0.5 V

B
0V

C
1.0 V

D
0.33 V

Solution

Standard electrode potential of hydrogen electrode under standard conditions is taken as 0V by convention.
Question 7
1 / -0

On diluting the concentration of mercurous chloride ten times, the potential of mercuric to mercurous at 298 K is

A
increased by 0.059 V

B
decreased by 0.059 V

C
increased by 0.02915 V

D
decreased by 0.02915 V
Question 8
1 / -0

Which of the following is mostly used as a reference electrode?

A
ZnCl₂

B
CuSO₄

C
Na₂SO₃

D
Hg₂Cl₂
Question 9
1 / -0

The reaction that takes place at anode in a dry cell is

A
Mn²+ 2e^-→ Mn (s)

B
Mn (s) → Mn⁺ + e^- + 1.5 V

C
Zn²⁺(s) + 2e^- → Zn (s)

D
Zn (s) → Zn⁺² + 2e^-
Question 10
1 / -0

When a rod of metallic lead was introduced into 0.01 M solution of Co (en)₂²⁺, it was found that 68% of the cobalt complex was reduced to Co (en)₃²⁺ by lead. If is – 0.126 V, E⁰ (Co (en)₃³⁺/Co (en)₃²⁺) is

A
– 0.0536 V

B
+ 0.0536 V

C
– 0.18 V

D
+ 0.18 V
Question 11
1 / -0

Hydrogen-oxygen fuel cells are used in spacecrafts to supply

A
oxygen

B
hydrogen

C
water

D
illumination
Question 12
1 / -0

An electrochemical cell is represented as follows.

Pt (H₂, 1 atm) | 0.1 M HCl || 0.1 M acetic acid | (H₂, 1 atm) Pt

The emf of this cell will not be zero because the

A
pH values of 0.1 M HCl and 0.1 M acetic acid are not the same

B
acids used in two compartments are different

C
emf of a cell depends on the molarities of acids used

D
temperature is constant

Question 13

1 / -0

Directions: Match Column–I with Column–II and indicate your answer by selecting the appropriate option.

Column–I	Column–II
(A) Standard hydrogen electrode	(a) Chemical equivalent/Faraday
(B) Electrochemical equivalent	(b) G^o < 0
(C) E⁰ > 0	(c) Calibration of potentiometer
(D) Weston cadmium cell	(d) E⁰ = 0 at all temperatures

(A) – (d), (B) – (a), (C) – (b), (D) – (c)

(A) – (a), (B) – (d), (C) – (b), (D) – (c)

(A) – (d), (B) – (a), (C) – (c), (D) – (b)

(A) – (c), (B) – (a), (C) – (b), (D) – (d)

Question 14
1 / -0

Consider the following disproportionation:

2ClO₃^– ClO₄^– + ClO₂^–
If the initial concentration of perchlorate ion is 0.1 M, then what would be its concentration at equilibrium at 298 K?
[= 0.36 V and = 0.33 V]

A
0.02 M

B
0.03 M

C
0.1 M

D
0.05 M
Question 15
1 / -0

The standard reduction potential values of Cu²⁺/Cu and Cu²⁺/Cu⁺ are 0.337 and 0.153 V, respectively. The standard electrode potential of Cu⁺/Cu half cell is

A
0.49 V

B
0.368 V

C
0.521 V

D
0.184 V
Question 16
1 / -0

Which of the following statements is correct about metallic conduction?

A
Metallic conduction is carried out by the movement of ions.

B
It involves a change in the chemical properties of the conductor.

C
It involves the transfer of matter.

D
It decreases with increase in temperature.
Question 17
1 / -0

When a lead storage cell is charged,

A
sulphuric acid is consumed

B
sulphuric acid is formed

C
lead sulphate is formed

D
lead is consumed
Question 18
1 / -0

In electroplating, m g of silver is deposited when 4 A of current flows for 2 minutes. The amount (in g) of silver deposited by 6 A of current flowing for 40 seconds will be

A
4m

B

C

D
3m
Question 19
1 / -0

Difference between electronic and ionic (electrolytic) conductivity is that electronic conductance takes place in metals by movement of ________ and electrolytic conductance takes place in solutions by movement of -------

A
electron cloud and electrolytes

B
metals and ions

C
electrons and ions

D
ions and electrons

Solution

metallic substances allow electricity to pass through them by flow of electrons and electrolytes allow electricity to pass through them in molten state and in aqueous solution by charge carried by ions .
Question 20
1 / -0

The emf of Daniell cell (given below) at 298 K is E_1.

When concentration of ZnSO₄ is 1.0 M and that of CuSO₄ is 0.01 M, the emf is changed to E₂. What is the relationship between E₁ and E₂?

A
E₁ > E₂

B
E₁ < E₂

C
E₁ = E₂

D
E₂ = O ≠ E₁
Question 21
1 / -0

Kohlrausch law of independent migration of ions states

A
that limiting molar conductivity of an electrolyte can be represented as the difference of the individual contributions of the anion and cation of the electrolyte

B
limiting molar conductivity of anion and cation of the electrolyte with respect to nature of ions with which it is associated

C
that limiting molar conductivity of an electrolyte can be represented as the sum of the individual contributions of the anion and cation of the electrolyte

D
that molar conductivity of an electrolyte can be represented as the sum of the individual contributions of the anion and cation of the electrolyte

Solution

molar conductivity at infinite dilution for a given salt can be expressed as the sum of the individual contributions from the ions of the electrolyte.
Question 22
1 / -0

Nernst equation E = E^o - (RT/nF) lnQ indicates that the equilibrium constant K_c will be equal to Q when

A
E = E^o

B
RT/nF = 1

C
E^o = zero

D
E^o = 1
Question 23
1 / -0

On the basis of the information available from the reaction: 4Al + 3O₂ 2Al₂O₃; G = - 827 kJ mole^-1 of O₂,the minimum emf required to carry out electrolysis of Al₂O₃ is (1 F = 96500 C)

A
2.14 V

B
4.28 V

C
6.42 V

D
8.56 V
Question 24
1 / -0

The potential of a hydrogen electrode dipped in a solution of pH = 10 is (H₂ is passed at 1 atm)

A
zero

B
1 V

C
3 V

D
- 0.59 V
Question 25
1 / -0

When 'C' amperes of electricity is passed through an electrolytic solution for 't' seconds, 'm' gram metal is deposited on cathode. The equivalent weight 'E' of the metal would be

A

B

C

D