Give IUPAC name of : `CH_(2)=CH-CHO`

Explanation

To determine the IUPAC name of the compound `CH₂=CH-CHO`, we will follow these steps:

### Step 1: Identify the longest carbon chain
The compound has three carbon atoms. The longest continuous chain consists of three carbon atoms (C1, C2, and C3).

### Step 2: Identify the functional groups
In this compound, we have an aldehyde group (-CHO) attached to the first carbon (C1). Additionally, there is a double bond between the first carbon (C1) and the second carbon (C2).

### Step 3: Number the carbon chain
We will number the carbon chain starting from the end nearest to the functional group (the aldehyde group), which is at C1. Thus, the numbering will be:
- C1: CHO (aldehyde)
- C2: CH (part of the double bond)
- C3: CH₂

### Step 4: Determine the suffix for the functional groups
For aldehydes, the suffix used is "-al". The presence of a double bond indicates that we will use the suffix "-ene".

### Step 5: Combine the information
Since the longest chain has three carbons, the base name will be "prop". The double bond is located between C2 and C3, so we will indicate that with "2-ene". The aldehyde group is at C1, so we will indicate that with "1-al".

### Step 6: Write the final IUPAC name
Putting it all together, the IUPAC name of the compound is:
**Prop-2-enal**

### Summary of the steps:
1. Identify the longest carbon chain (3 carbons).
2. Identify the functional groups (aldehyde and double bond).
3. Number the carbon chain from the end nearest to the functional group.
4. Determine the suffixes for the functional groups.
5. Combine the information to form the name.
6. Write the final IUPAC name.