The IUPAC name of given compound is
`CH_3-underset(CH_2CH_3)underset(|)(CH)-CHO`

Options

A. Butan -2- aldehyde
B. 2- methylbutanal
C. 3 - methyl isobutyraldehyde
D. 2 - ethylpropanal

Answer

To determine the IUPAC name of the given compound `CH3-CH(CH2CH3)-CHO`, we will follow these steps:

### Step 1: Identify the Longest Carbon Chain
The first step in naming an organic compound is to identify the longest continuous carbon chain. In this case, we can see that the longest chain consists of 4 carbon atoms.

### Step 2: Number the Carbon Chain
Once the longest chain is identified, we need to number the carbon atoms in the chain. We will number from the end nearest to the functional group (aldehyde, -CHO). This gives us the following numbering:
1. CHO (carbon 1)
2. CH (carbon 2)
3. CH2 (carbon 3)
4. CH3 (carbon 4)

### Step 3: Identify the Functional Group
The functional group present in this compound is an aldehyde (-CHO), which is located at carbon 1. Aldehydes are named with the suffix "-al".

### Step 4: Identify Substituents
Next, we need to identify any substituents attached to the main carbon chain. In this case, there is a methyl group (CH3) attached to carbon 2.

### Step 5: Combine Information for Naming
Now we can combine the information to write the IUPAC name. The longest chain has 4 carbon atoms, which corresponds to "butane". Since we have an aldehyde functional group, we change "butane" to "butanal". Additionally, we have a methyl substituent at carbon 2, which we denote as "2-methyl".

### Final IUPAC Name
Putting it all together, the IUPAC name of the compound is **2-methylbutanal**.

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