In which of the following reaction `t-`butylbenzene is formed :

Options

A. Benzene `+ t-`butyl chloride `overset(AlCl_(3))rarr`
B. Benzene `+(CH_(3))_(2)C=CH_(2)overset(BF_(3).HF)rarr`
C. Benzene + `t-butyl alcohol overset(H_(2)SO_(4))to`
D. All of these

Explanation

To determine in which of the given reactions `t-butylbenzene` is formed, we can analyze each reaction step-by-step.

### Step-by-Step Solution:

1. **Identify the Reactions:**
We need to analyze the three reactions provided in the question to see if they lead to the formation of `t-butylbenzene`.

2. **First Reaction: Friedel-Crafts Alkylation:**
- In this reaction, `t-butyl chloride` is reacted with `benzene` in the presence of a `Lewis acid` (like AlCl3).
- The `t-butyl chloride` can be represented as (CH3)3CCl.
- The Lewis acid facilitates the formation of a `t-butyl cation` (a tertiary carbocation).
- This cation then reacts with benzene, replacing one of the hydrogen atoms, resulting in the formation of `t-butylbenzene`.
- **Conclusion:** This reaction produces `t-butylbenzene`.

3. **Second Reaction: Alkene Reaction with Benzene:**
- Here, benzene is reacted with an alkene, specifically (CH3)2C=CH2 (which is isobutylene).
- The double bond in the alkene breaks, and the carbon with the double bond attaches to the benzene ring.
- This carbon is connected to three other carbons (making it a tertiary carbon), leading to the formation of `t-butylbenzene`.
- **Conclusion:** This reaction also produces `t-butylbenzene`.

4. **Third Reaction: Reaction of Tertiary Butyl Alcohol:**
- In this case, `t-butyl alcohol` (which can be represented as (CH3)3COH) is reacted in the presence of sulfuric acid (H2SO4).
- The acid protonates the alcohol, leading to the formation of a `t-butyl cation`.
- This cation then reacts with benzene, replacing one hydrogen atom and forming `t-butylbenzene`.
- **Conclusion:** This reaction also produces `t-butylbenzene`.

5. **Final Conclusion:**
Since all three reactions lead to the formation of `t-butylbenzene`, the answer to the question is that `t-butylbenzene` is formed in all of the reactions.

### Answer:
All of these reactions produce `t-butylbenzene`.

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