Assertion (A): Following are the structural isomers of boutane.
`H-underset(H)underset(|)overset(H)overset(|)(C)-underset(H)underset(|)overset(H)overset(|)(C)-underset(H)underset(|)overset(H)overset(|)(C)-underset(H)underset(|)overset(H)overset(|)(C)-H`
`H-underset(H)underset(|)overset(H)overset(|)(C)-underset(H-underset(H)underset(|)(C)-H)underset(|)overset(H)overset(|)(C)-underset(H)underset(|)overset(H)overset(|)(C)-H`
Reason (R): Structural isomers have the same molecular formula but they differ in their structures.

Options

A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is NOT the correct explanation of A.
C. A is true but R is false.
D. A is false and R is true.

Explanation

To solve the question regarding the assertion and reason provided about structural isomers of butane, let's break it down step by step.

### Step 1: Understand the Assertion
The assertion states that the given structures are structural isomers of butane.

### Step 2: Define Structural Isomers
Structural isomers are compounds that have the same molecular formula but different structural arrangements of atoms.

### Step 3: Identify the Molecular Formula of Butane
Butane is a hydrocarbon with the molecular formula C4H10.

### Step 4: Identify the Possible Structural Isomers of Butane
For butane (C4H10), there are two structural isomers:
1. **n-Butane**: A straight-chain structure (CH3-CH2-CH2-CH3).
2. **Isobutane (or methylpropane)**: A branched structure (CH3-CH(CH3)-CH3).

### Step 5: Analyze the Given Structures
The assertion claims that the provided structures are isomers of butane. We need to verify if they represent the two known isomers of butane:
- The first structure represents n-butane (straight chain).
- The second structure represents isobutane (branched).

### Step 6: Evaluate the Reason
The reason states that structural isomers have the same molecular formula but differ in their structures. This is a true statement, as it accurately describes the nature of structural isomers.

### Step 7: Conclusion
Both the assertion and the reason are correct. The assertion correctly identifies the structures as isomers of butane, and the reason correctly explains what structural isomers are.

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

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