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NEET CHEMISTRYElectrochemistryMedium

Question

The molar conductance of an electrolyte increases with dilution according to the equation: Λm=ΛmAc\Lambda_m = \Lambda^{\circ}_m - A\sqrt{c} Consider the following four statements: A: This equation applies to both strong and weak electrolytes. B: The value of the constant AA depends upon the nature of the solvent. C: The value of constant AA is the same for both BaCl2\text{BaCl}_2 and MgSO4\text{MgSO}_4. D: The value of constant AA is the same for both BaCl2\text{BaCl}_2 and Mg(OH)2\text{Mg(OH)}_2. Which of the above statements are correct?

A

(A) and (B) only

B

(A), (B), and (C) only

C

(B) and (C) only

D

(B) and (D) only

Step-by-Step Solution

According to the Debye-Hückel-Onsager equation, Λm=ΛmAc\Lambda_m = \Lambda^{\circ}_m - A\sqrt{c} . Statement A: This equation applies only to strong electrolytes, as weak electrolytes show a steep increase in molar conductivity with dilution, which cannot be represented by this linear equation. So, statement A is incorrect. Statement B: The constant AA depends on the nature of the solvent (dielectric constant, viscosity) and temperature. So, statement B is correct. Statements C & D: The value of AA also depends on the type of electrolyte, i.e., the charges on the cation and anion produced upon dissociation. BaCl2\text{BaCl}_2 dissociates into Ba2+\text{Ba}^{2+} and 2Cl2\text{Cl}^-, making it a 2-1 electrolyte. MgSO4\text{MgSO}_4 dissociates into Mg2+\text{Mg}^{2+} and SO42\text{SO}_4^{2-}, making it a 2-2 electrolyte. Thus, they have different values of AA. However, Mg(OH)2\text{Mg(OH)}_2 dissociates into Mg2+\text{Mg}^{2+} and 2OH2\text{OH}^-, making it a 2-1 electrolyte just like BaCl2\text{BaCl}_2. Therefore, they have the same value for constant AA. Thus, statement C is incorrect and statement D is correct. Hence, only statements (B) and (D) are correct.

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from Electrochemistry. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

CHEMISTRYElectrochemistryconductanceelectrolyteincreasesdilutionaccording

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