(i) 

Step 1:

The formula of a given compound is CH₃CH(CH₃)CH₂CH₂CHO. In the given compound, aldehyde carbon gets the least position. The structure of the compound with the numbering system is as follows:



Step 2:

The parent chain contains 5 carbon atoms, hence, its name is pentanal and a methyl group is attached to a fourth carbon atom. 

The IUPAC name of the compound is 4-Methylpentanal

(ii)

Step 1:

The molecular formula of the compound is CH₃CH₂COCH(C₂H₅)CH₂CH₂Cl and the structure is as follows:


The main functional group is a ketone, hence, the numbering will be done in such a way that ketone carbon gets the lowest position. 


Step 2:

The Cl atom is present at 6 carbon for which chloro is used, an ethyl group is present at the 4th carbon atom and the parent chain name is hexan-3-one. 
The IUPAC name of the compound is 6-Chloro-4-ethylhexan-3-one.

(iii)

Step 1:

The molecular formula of the compound is CH₃CH=CHCHO and the structure is as follows:

The compound contains two functional groups, that is, aldehyde and a double bond. The aldehyde gets higher priority than the double bond, hence, aldehyde carbon gets the lowest numbering. The structure of the compound with numbering is as follows:



Step 2:

The parent chain contains a double bond at second carbon for which 'en' is used. The IUPAC name of the compound is 
But-2-en-1-al

(iv)

Step 1:

The molecular formula of the compound is CH₃COCH₂COCH₃. The structure is as follows:


The parent chain contains two ketone groups hence dione is used as a suffix. 

Step 2:

The structure of the compound with a numbering system is as follows: 


The IUPAC name of the compound is pentane-2,4-dione.

(v)

Step 1:

The molecular formula of the compound is CH₃CH(CH₃)CH₂C(CH₃)₂COCH₃. The structure of the compound is as follows:



The main functional group is the ketone group hence, it gets the lowest position.

Step 2:
The structure of the compound with numbering is as follows:



The parent chain contains 6 carbon atoms. Two methyl groups at 2rd and one methyl group at the 5th position.  Hence, tri is used for the methyl group.

The IUPAC name of the compound is 3,3,5-Trimethylhexan-2-one

(vi)

Step 1: 

The molecular formula of the compound is (CH₃)₃CCH₂COOH. The structure is as follows: 


The carboxylic group is the main functional group. The carboxylic carbon gets the lowest number. 

Step 2:

The structure with numbering is as follows:



The parent chain name is butanoic acid, and two methyl groups are present at the third carbon atom. 

The IUPAC name of the compound is 3,3-Dimethylbutanoic acid.

(vii)

Step 1:
 
The molecular formula is OHCC₆H₄CHO-p. The structure of the compound is as follows:



Step 2:

When aldehyde carbon is not included in the chain then carbaldehyde is used as a suffix. 

The IUPAC name of the compound is Benzene-1,4-dicarbaldehyde.