Assertion : Saturated hydrocarbons are chemically less reactive.
Reason : All the valencies of carbon atom are satisfied by single covalent bonds.

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 analyze the assertion and reason provided in the question, we will break it down step by step.

### Step 1: Understand the Assertion
The assertion states that "Saturated hydrocarbons are chemically less reactive."
- **Explanation**: Saturated hydrocarbons, such as alkanes, contain only single bonds between carbon atoms. This structure makes them relatively stable and less prone to chemical reactions compared to unsaturated hydrocarbons, which contain double or triple bonds.

### Step 2: Understand the Reason
The reason states that "All the valencies of carbon atoms are satisfied by single covalent bonds."
- **Explanation**: Carbon has four valencies, meaning it can form four bonds. In saturated hydrocarbons, all four of these valencies are satisfied by single covalent bonds. This saturation leads to a stable structure, which contributes to the lower reactivity of these compounds.

### Step 3: Connect Assertion and Reason
Now, we need to determine if the reason correctly explains the assertion.
- The assertion is true because saturated hydrocarbons are indeed less reactive.
- The reason is also true because the stability provided by single covalent bonds does explain why these hydrocarbons are less reactive.

### Conclusion
Both the assertion and the reason are correct, and the reason provides a valid explanation for the assertion. Therefore, the correct conclusion is that both statements are true, and the reason is a correct explanation of the assertion.

### Final Answer
- **Assertion**: True
- **Reason**: True
- **Conclusion**: The reason is a correct explanation of the assertion.

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