This section contains assertion and reason type questions. Each question has 4 choice (1), (2),(3), and (4), out of which only one is correct.
Assertion (A) IUPAC name of neopentane is 2,2 – dimethylpropane.
Reason ( R) Neopentane has one quaternary and four primary carbon atoms.

Options

A. Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion
B. Both Assertion and Reason are correct but reason is not the correct explanation of Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect

Answer

To solve the assertion and reason question regarding neopentane, we will break it down step by step.

### Step 1: Analyze the Assertion
The assertion states: "IUPAC name of neopentane is 2,2-dimethylpropane."

- Neopentane has the molecular formula C5H12.
- Its structure can be represented as follows:

```
CH3
|
CH3 - C - CH3
|
CH3
```

- In this structure, we can see that there is a central carbon atom (C) bonded to four methyl groups (CH3).
- To determine the IUPAC name, we need to identify the longest continuous carbon chain. The longest chain here consists of three carbon atoms (propane).
- Since there are two methyl groups attached to the second carbon of the propane chain, the correct IUPAC name is indeed 2,2-dimethylpropane.

### Conclusion for Step 1:
The assertion is **true**.

### Step 2: Analyze the Reason
The reason states: "Neopentane has one quaternary and four primary carbon atoms."

- A quaternary carbon atom is one that is bonded to four other carbon atoms. In neopentane, the central carbon atom is bonded to four methyl groups, making it a quaternary carbon.
- The other four carbon atoms (the methyl groups) are each bonded to only one carbon atom, making them primary carbons.

### Conclusion for Step 2:
The reason is also **true**.

### Step 3: Determine the Relationship
Now we need to determine if the reason correctly explains the assertion.

- While both the assertion and the reason are true, the reason does not provide a correct explanation for the assertion. The IUPAC name of neopentane is derived from its structure and the longest carbon chain, not specifically because of the types of carbon atoms present.

### Final Conclusion:
Both the assertion and reason are true, but the reason is not the correct explanation for the assertion. Therefore, the correct answer is option (2).

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