A hydrocarbon has three carbon atoms. Write down its molecular formulae as
alkene

Explanation

To find the molecular formula of an alkene with three carbon atoms, we can follow these steps:

### Step 1: Identify the number of carbon atoms
Since the hydrocarbon has three carbon atoms, we denote this as C₃.

### Step 2: Determine the type of hydrocarbon
We are looking for an alkene, which is characterized by having at least one double bond between carbon atoms.

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