Answer :
Answer:
Here are the molecular structures based on the given IUPAC names:
### a) 3-ethyl-1,4-dimethylcyclopent-1-ene
**Structure Description:**
- A cyclopentene ring (a five-membered ring with one double bond).
- An ethyl group (–CH₂CH₃) attached to the third carbon of the ring.
- Two methyl groups (–CH₃) attached to the first and fourth carbons of the ring.
**Drawing:**
```
CH₂CH₃
|
CH₃-C₁
/ \
CH₃-C₄ C₂
\ /
C₅
|
C=C
```
### b) (E)-3-chloro-4-phenylbut-2-en-2-ol
**Structure Description:**
- A butene backbone with a double bond between C2 and C3.
- A chloro group (–Cl) at the third carbon.
- A phenyl group (–C₆H₅) at the fourth carbon.
- An alcohol group (–OH) at the second carbon.
- The E configuration indicates the highest priority groups are on opposite sides of the double bond.
**Drawing:**
```
OH
|
C₁= C₂-C₃- C₄-C₆H₅
|
Cl
```
### c) (Z)-1-bromo-2-methylbut-1-en-3-yn-1-amine
**Structure Description:**
- A butene backbone with a double bond between C1 and C2.
- A bromo group (–Br) and an amine group (–NH₂) at the first carbon.
- A methyl group (–CH₃) at the second carbon.
- A triple bond (–C≡C–) at the third carbon.
- The Z configuration indicates the highest priority groups are on the same side of the double bond.
**Drawing:**
```
NH₂
|
Br-C₁= C₂-C≡C-C₄
|
CH₃
```
### d) N-ethyl-N-methyl-1-phenylethan-1-amine
**Structure Description:**
- An ethanamine backbone (two carbon atoms with an amine group).
- A phenyl group (–C₆H₅) attached to the first carbon.
- An ethyl group (–CH₂CH₃) and a methyl group (–CH₃) both attached to the nitrogen atom.
**Drawing:**
```
CH₃
|
N-CH₂CH₃
|
C₆H₅
|
C₂H₅
```
### e) sec-butyl ethyl ketone
**Structure Description:**
- A ketone group (–C=O) with an ethyl group (–CH₂CH₃) attached to the carbonyl carbon.
- The butyl group is attached in the secondary position (sec-butyl).
**Drawing:**
```
CH₃
|
CH₃-CH₂-CO-CH₂CH₃
|
CH₂CH₃
```
These drawings provide a basic representation of the structures based on the IUPAC names given.
