`R- NO_(2) overset(HNO_(2))rarr X overset(NaOH)rarr` Blue colour in above reaction R is

Options

A. `CH_(3)-`
B. `CH_(3)CH_(2)-`
C. `CH_(3)CH_(2)CH_(2)-`
D. `CH_(3)- underset(underset(CH_(3))(|))(C)H-`

Explanation

To solve the given reaction sequence and identify the alkyl group R that leads to the formation of a blue color, we can follow these steps:

### Step 1: Identify the structure of the nitro compound
The starting compound is represented as R-NO₂. We need to determine the structure of R that will lead to the formation of a blue color in the final product.

### Step 2: Consider possible alkyl groups
We are looking for an alkyl group R that is likely to produce a blue color when reacted with HNO₂ and then with NaOH. Common alkyl groups to consider are methyl (CH₃), ethyl (C₂H₅), isopropyl (C₃H₇), and others.

### Step 3: Analyze the reaction with HNO₂
When R-NO₂ is treated with HNO₂, it undergoes a reaction that typically involves the formation of a diazonium compound. The structure of R will influence the stability of the resulting compound.

### Step 4: Determine the specific alkyl group
After analyzing the possible alkyl groups, we find that isopropyl (C₃H₇) is a suitable candidate. The reaction would yield isopropyl nitrite (C₃H₇-NO) upon reaction with HNO₂.

### Step 5: Reaction with NaOH
When isopropyl nitrite is treated with NaOH, it forms a pseudo-nitro compound. This compound is known to produce a blue color when dissolved in an alkaline solution.

### Step 6: Conclusion
Based on the analysis, the alkyl group R that leads to the formation of a blue color in the reaction is isopropyl (C₃H₇).

### Final Answer:
R is isopropyl (C₃H₇).

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