The correct answer is A. Dilution.
The degree of dissociation of an electrolyte is the fraction of the total number of molecules that are dissociated into ions. It is a measure of how strongly the electrolyte is dissociated. The degree of dissociation increases with dilution. This is because the concentration of the electrolyte decreases as it is diluted, which makes it easier for the ions to separate from each other.
The other options are incorrect. Impurities do not affect the degree of dissociation of an electrolyte. Atmospheric pressure does not affect the degree of dissociation of an electrolyte. The method of dissolution does not affect the degree of dissociation of an electrolyte.
Here is a more detailed explanation of each option:
- A. Dilution: The degree of dissociation of an electrolyte increases with dilution. This is because the concentration of the electrolyte decreases as it is diluted, which makes it easier for the ions to separate from each other.
- B. Impurities: Impurities do not affect the degree of dissociation of an electrolyte. This is because the impurities do not interact with the ions of the electrolyte.
- C. Atmospheric pressure: Atmospheric pressure does not affect the degree of dissociation of an electrolyte. This is because the ions of the electrolyte are not affected by the pressure of the atmosphere.
- D. Method of dissolution: The method of dissolution does not affect the degree of dissociation of an electrolyte. This is because the ions of the electrolyte are formed when the electrolyte dissolves in water, regardless of the method of dissolution.