Assertion : Precipitation of silver chloride occurs instantaneously by mixing of aqueous solutions of silver nitrate and sodium chloride.
Reason : Ionic reactions occur very fast.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that "Precipitation of silver chloride occurs instantaneously by mixing of aqueous solutions of silver nitrate and sodium chloride."

- When silver nitrate (AgNO₃) and sodium chloride (NaCl) are mixed in aqueous solution, they dissociate into their respective ions:
- AgNO₃ → Ag⁺ + NO₃⁻
- NaCl → Na⁺ + Cl⁻

- When these solutions are mixed, the Ag⁺ ions react with Cl⁻ ions to form silver chloride (AgCl), which is an insoluble precipitate:
- Ag⁺ + Cl⁻ → AgCl (s)

- This reaction occurs almost instantaneously upon mixing the solutions, leading to the formation of a white precipitate of silver chloride.

### Step 2: Understand the Reason
The reason states that "Ionic reactions occur very fast."

- Ionic reactions are typically fast because they involve the interaction of ions in solution. When ionic compounds dissolve in water, they dissociate into their constituent ions, which are free to move and react with each other.

- The formation of a precipitate, like AgCl, is a result of the rapid collision and reaction of these ions in the solution.

### Step 3: Conclusion
Both the assertion and the reason are true. The reason correctly explains why the assertion is true: the fast nature of ionic reactions leads to the instantaneous precipitation of silver chloride when the two solutions are mixed.

### Final Answer
Both assertion and reason are true, and the reason is the correct explanation of the assertion.

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