Complete the following statements by selecting the correct alternative from the choices given :
In the dehydration of alcohols to alkenes by heating with concentrated sulphuric acid, the initiation step is :

Options

A. formation of carbocation
B. formation of an ester
C. protonation of alcohol molecule
D. elimination of water

Explanation

To solve the question regarding the initiation step in the dehydration of alcohols to alkenes by heating with concentrated sulphuric acid, we can break down the process into clear steps:

### Step-by-Step Solution:

1. **Understanding the Reaction**: The dehydration of alcohols involves converting an alcohol into an alkene by removing a water molecule. This process typically requires an acid catalyst, in this case, concentrated sulphuric acid.

2. **Identifying the Initiation Step**: The first step in the mechanism of dehydration is crucial. When an alcohol (like ethanol) is treated with concentrated sulphuric acid, the first action is the protonation of the alcohol.

3. **Protonation of Alcohol**: In this step, the alcohol molecule (e.g., ethanol) donates a lone pair of electrons to a proton (H⁺) from the sulfuric acid. This results in the formation of a protonated alcohol (also known as an oxonium ion). The hydroxyl group (OH) becomes positively charged, making it a better leaving group.

4. **Formation of Carbocation**: After protonation, the next step involves the loss of a water molecule from the protonated alcohol, leading to the formation of a carbocation. This is a key intermediate in the reaction.

5. **Formation of Alkene**: Finally, the carbocation undergoes a rearrangement or elimination of a proton (H⁺) to form the alkene.

### Conclusion:
The initiation step in the dehydration of alcohols to alkenes by heating with concentrated sulphuric acid is the **protonation of the alcohol molecule**.

### Answer:
The correct alternative is: **Protonation of the alcohol molecule.**

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