Iupac naming of ch3ch(ch3)ch2ch2cho

4-Methylpentanal  

Explanation:

1. Find the longest continuous chain that contains the carbonyl carbon

The longest chain contains five carbon atoms (pentane).

2. Identify the functional group

The functional group is an aldehyde.

You form the name of an aldehyde by dropping the -e from that of the parent alkane and adding the ending -al.

pentane - "-e" + "-al" ⟶ pentanal

3. Number the C atoms of the main chain.

The aldehyde is automatically C1.

4. Identify any substituents

There is a methyl group on C4.

5. Attach the name of the substituent to that of the parent.

The name becomes methylpentanal.

6. Add the locant

The locant is the locating number (4). Join it to the name with a hyphen.

The IUPAC name is 4-methylpentanal.