chemistry : class12 Strong Electrolytes : Conductance in electrolytic solutions : Electrochemistry MCQ Questions and Answers
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Strong Electrolytes
MCQ questions and answers.
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MCQ Questions
1. Which of the following is a strong electrolyte in aqueous solution?
A.
CH3COOH
B.
NH4OH
C.
NaCl
D.
H2CO3
Correct Answer:
NaCl
Explanation:
NaCl is a strong electrolyte because it dissociates almost completely into Na+ and Cl− ions in aqueous solution.
2. Strong electrolytes conduct electricity mainly because they produce:
A.
A small number of neutral molecules
B.
A large concentration of ions
C.
Only electrons in solution
D.
Only solvent molecules
Correct Answer:
A large concentration of ions
Explanation:
Strong electrolytes dissociate almost completely in solution, producing a high concentration of mobile ions that carry electric current.
3. Which of the following undergoes almost complete ionization in water?
A.
HCl
B.
CH3COOH
C.
NH4OH
D.
HCN
Correct Answer:
HCl
Explanation:
HCl is a strong electrolyte and ionizes almost completely in water to form H+ and Cl− ions.
4. On dilution, the molar conductivity of a strong electrolyte generally:
A.
Decreases sharply
B.
Increases gradually
C.
Becomes zero
D.
Remains exactly constant
Correct Answer:
Increases gradually
Explanation:
For strong electrolytes, dilution reduces interionic attraction, allowing ions to move more freely, so molar conductivity increases gradually.
5. The limiting molar conductivity of a strong electrolyte is represented by:
A.
Λm
B.
Λm°
C.
κ°
D.
G°
Correct Answer:
Λm°
Explanation:
Λm° denotes the limiting molar conductivity of an electrolyte at infinite dilution, where interionic interactions are minimal.
6. For a strong electrolyte, which statement is correct at ordinary concentrations?
A.
It is completely unionized
B.
It is almost completely dissociated
C.
It contains no solvent molecules
D.
It conducts only through neutral molecules
Correct Answer:
It is almost completely dissociated
Explanation:
Strong electrolytes are almost completely dissociated into ions in solution, which accounts for their good electrical conductivity.
7. Which electrolyte is expected to have the highest conductivity when present at the same concentration as the others?
A.
A strong electrolyte with many mobile ions
B.
A weak electrolyte with few ions
C.
A non-electrolyte
D.
Pure water with no dissolved substance
Correct Answer:
A strong electrolyte with many mobile ions
Explanation:
At the same concentration, a strong electrolyte produces more mobile ions than a weak electrolyte or non-electrolyte and therefore conducts better.
8. The variation of molar conductivity of a strong electrolyte with concentration is commonly expressed by:
A.
Λm = Λm° − K√c
B.
Λm = Λm° + Kc
C.
Λm = K√c
D.
Λm = c/Λm°
Correct Answer:
Λm = Λm° − K√c
Explanation:
For strong electrolytes, molar conductivity follows the relation Λm = Λm° − K√c, where K is a constant and c is the concentration.
9. At infinite dilution, the ions of a strong electrolyte move with:
A.
Maximum interionic attraction
B.
Minimum freedom
C.
Nearly independent movement
D.
No electrical mobility
Correct Answer:
Nearly independent movement
Explanation:
At infinite dilution, ions of a strong electrolyte are far apart and experience negligible interionic attraction, so they move nearly independently.
10. Which of the following is a strong electrolyte that dissociates into three ions per formula unit in water?
A.
NaCl
B.
KNO3
C.
CaCl2
D.
CH3COOH
Correct Answer:
CaCl2
Explanation:
CaCl2 is a strong electrolyte and dissociates almost completely as CaCl2 → Ca2+ + 2Cl−, producing three ions per formula unit.
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