chemistry : class12 Ionic Mobility : Conductance in electrolytic solutions : Electrochemistry MCQ Questions and Answers
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Ionic Mobility
MCQ questions and answers.
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MCQ Questions
1. Ionic mobility is defined as the speed attained by an ion per unit electric field strength. Which expression represents ionic mobility?
A.
u = vE
B.
u = v/E
C.
u = E/v
D.
u = E + v
Correct Answer:
u = v/E
Explanation:
Ionic mobility (u) is the drift velocity (v) of an ion divided by the applied electric field strength (E).
2. What is the SI unit of ionic mobility?
A.
S m⁻¹
B.
mol m⁻³
C.
m² V⁻¹ s⁻¹
D.
C mol⁻¹
Correct Answer:
m² V⁻¹ s⁻¹
Explanation:
From u = v/E, the SI unit is (m s⁻¹)/(V m⁻¹), which simplifies to m² V⁻¹ s⁻¹.
3. If two ions are placed in the same electric field, the ion with greater ionic mobility will have:
A.
A lower drift velocity
B.
A greater drift velocity
C.
Zero drift velocity
D.
The same drift velocity in every case
Correct Answer:
A greater drift velocity
Explanation:
At the same electric field, drift velocity is directly proportional to ionic mobility, according to v = uE.
4. An ion has a mobility of 2.0 × 10⁻⁸ m² V⁻¹ s⁻¹ in an electric field of 100 V m⁻¹. What is its drift velocity?
A.
2.0 × 10⁻⁶ m s⁻¹
B.
2.0 × 10⁻⁸ m s⁻¹
C.
5.0 × 10⁻⁶ m s⁻¹
D.
2.0 × 10⁻¹⁰ m s⁻¹
Correct Answer:
2.0 × 10⁻⁶ m s⁻¹
Explanation:
Using v = uE, v = (2.0 × 10⁻⁸)(100) = 2.0 × 10⁻⁶ m s⁻¹.
5. At a fixed electric field strength, an ion's drift velocity increases when its ionic mobility:
A.
Decreases
B.
Becomes zero
C.
Increases
D.
Changes its sign only
Correct Answer:
Increases
Explanation:
The relation v = uE shows that drift velocity increases directly with ionic mobility when the electric field is constant.
6. Which factor directly affects the mobility of an ion in an electrolytic solution?
A.
The size and charge of the ion
B.
The colour of the solution
C.
The shape of the container
D.
The material of the external wire only
Correct Answer:
The size and charge of the ion
Explanation:
Ionic mobility depends on the movement of the ion through the solvent and is influenced by its charge and effective size.
7. If the electric field acting on an ion is doubled while its ionic mobility remains constant, its drift velocity will:
A.
Be halved
B.
Remain unchanged
C.
Become double
D.
Become zero
Correct Answer:
Become double
Explanation:
Since v = uE and u is constant, doubling the electric field doubles the drift velocity.
8. An ion has a drift velocity of 4.0 × 10⁻⁵ m s⁻¹ in an electric field of 200 V m⁻¹. Its ionic mobility is:
A.
2.0 × 10⁻⁷ m² V⁻¹ s⁻¹
B.
8.0 × 10⁻³ m² V⁻¹ s⁻¹
C.
5.0 × 10⁶ m² V⁻¹ s⁻¹
D.
2.0 × 10⁻² m² V⁻¹ s⁻¹
Correct Answer:
2.0 × 10⁻⁷ m² V⁻¹ s⁻¹
Explanation:
Using u = v/E, u = (4.0 × 10⁻⁵)/200 = 2.0 × 10⁻⁷ m² V⁻¹ s⁻¹.
9. Which statement about ionic mobility is correct?
A.
It is independent of the electric field in the usual dilute-solution approximation
B.
It is always equal to the ionic charge
C.
It has the unit mol L⁻¹
D.
It is the distance travelled by an ion in one second without an electric field
Correct Answer:
It is independent of the electric field in the usual dilute-solution approximation
Explanation:
Ionic mobility is a characteristic measure of an ion's response to an electric field and is treated as constant at ordinary field strengths.
10. Two ions have the same drift velocity, but the first ion moves in an electric field twice as strong as that for the second ion. Which ion has greater mobility?
A.
The first ion
B.
The second ion
C.
Both have zero mobility
D.
Both must have equal mobility
Correct Answer:
The second ion
Explanation:
From u = v/E, for the same drift velocity, mobility is greater in the weaker electric field. Therefore, the second ion has greater mobility.
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