Assertion : `underset("2-chloro-4-methylpentanal.")(CH_(3)-underset(Cl)underset(|)(CH)-CH_(2)-underset(CH_(3))underset(|)(CH)-CHO)` is
Reason : Names are not to be written according to the alphabetical order of substituents.

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.

Explanation

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

### Step 1: Understand the Assertion
The assertion states that the compound is named as "2-chloro-4-methylpentanal." We need to verify if this name is correct based on IUPAC nomenclature rules.

### Step 2: Identify the Structure
The structure given is:
- CH3-CH(Cl)-CH2-CH(CH3)-CHO
This indicates that:
- There are five carbon atoms (pentane).
- There is an aldehyde functional group (CHO) at the end of the chain.
- There are two substituents: a chloro group (Cl) and a methyl group (CH3).

### Step 3: Determine the Correct Naming
According to IUPAC nomenclature:
- The functional group (aldehyde) has the highest priority and should be numbered first.
- The longest carbon chain containing the functional group is identified, which is pentane in this case.
- Number the chain starting from the end nearest to the aldehyde group.

The numbering will be:
1. CHO (1)
2. CH2 (2)
3. CH (3)
4. CH (4)
5. CH3 (5)

### Step 4: Identify the Positions of Substituents
- The methyl group (CH3) is on carbon 2.
- The chloro group (Cl) is on carbon 4.

### Step 5: Write the Correct Name
According to the IUPAC rules:
- The correct name should be "4-chloro-2-methylpentanal" (not "2-chloro-4-methylpentanal").

### Step 6: Analyze the Reason
The reason states that "names are not to be written according to the alphabetical order of substituents." This is misleading because while the substituents are named alphabetically, the numbering is based on the priority of the functional group. Thus, the reason is also incorrect.

### Conclusion
Both the assertion and the reason are incorrect. The correct name is "4-chloro-2-methylpentanal," and the reason provided does not accurately reflect the rules of IUPAC nomenclature.

### Final Answer
Both the assertion and reason are false.

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