The IUPAC name for the formula
`{:(" "CH_(3)),(" |"),(CH_(3)-C=CH-COOH):}` is

Options

A. 2-Methylbut-2-enoic acid
B. 3-Methylbut-3-enoic acid
C. 3-Methylbut-2-enoic acid
D. 2-Methylbut-3-enoic acid

Explanation

To determine the IUPAC name for the compound with the formula CH₃-CH₃-C=CH-COOH, we can follow these steps:

### Step 1: Identify the Longest Carbon Chain
The first step in naming an organic compound is to identify the longest continuous chain of carbon atoms. In this case, the longest chain consists of four carbon atoms:

```
CH₃
|
CH₃-C=CH-COOH
```

### Step 2: Number the Carbon Chain
Next, we need to number the carbon chain. The numbering should start from the end closest to the functional group, which in this case is the carboxylic acid (-COOH) group. Therefore, we number the chain as follows:

```
1 - COOH
2 - C
3 - C (with a double bond)
4 - C (with a methyl group)
```

So, the numbering will be:
1. COOH
2. C (double bond)
3. C (methyl group)
4. C (methyl group)

### Step 3: Identify the Substituents and Functional Groups
Now we can identify the substituents and functional groups:
- The longest chain has 4 carbon atoms, which corresponds to the prefix "but-".
- There is a double bond between the 2nd and 3rd carbon atoms, so we use the suffix "-ene" and indicate its position with "2".
- There is a methyl group (CH₃) on the 3rd carbon, which we denote as "3-methyl".
- The carboxylic acid group (-COOH) indicates that the compound is an acid, and we use the suffix "-oic acid".

### Step 4: Combine the Information
Putting all this information together, we can construct the IUPAC name:
- The base name is "but" for the four carbon atoms.
- The double bond is at position 2, so we write "2-ene".
- The methyl group is at position 3, so we write "3-methyl".
- The carboxylic acid gives us the suffix "-oic acid".

Thus, the complete IUPAC name is **3-methylbut-2-enoic acid**.

### Final Answer
The IUPAC name for the compound CH₃-CH₃-C=CH-COOH is **3-methylbut-2-enoic acid**.

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