To draw the structures of the given IUPAC names, we will follow a systematic approach for each compound.
### (i) Hexa-2,4-diyne
1. **Identify the main chain**: The prefix "hexa-" indicates that there are 6 carbon atoms in the main chain.
2. **Number the carbon chain**: Number the carbon atoms from one end to the other. We can start from the left:
- 1, 2, 3, 4, 5, 6.
3. **Identify the positions of the triple bonds**: The name indicates triple bonds at positions 2 and 4.
4. **Draw the structure**: Place triple bonds between carbon atoms 2 and 3, and between carbon atoms 4 and 5. Fill the remaining valences with hydrogen atoms.
**Structure**:
```
H H H
| | |
H--C≡C--C--C≡C--C--H
| | |
H H H
```
### (ii) Pent-3-ene-1-yne
1. **Identify the main chain**: The prefix "pent-" indicates that there are 5 carbon atoms in the main chain.
2. **Number the carbon chain**: Number the carbon atoms from one end to the other. We can start from the left:
- 1, 2, 3, 4, 5.
3. **Identify the positions of the double and triple bonds**: The name indicates a double bond at position 3 and a triple bond at position 1.
4. **Draw the structure**: Place a double bond between carbon atoms 2 and 3, and a triple bond between carbon atoms 1 and 2. Fill the remaining valences with hydrogen atoms.
**Structure**:
```
H H
| |
H--C≡C--C==C--C--H
| |
H H
```
### (iii) Pent-1-en-4-yne
1. **Identify the main chain**: The prefix "pent-" indicates that there are 5 carbon atoms in the main chain.
2. **Number the carbon chain**: Number the carbon atoms from one end to the other. We can start from the left:
- 1, 2, 3, 4, 5.
3. **Identify the positions of the double and triple bonds**: The name indicates a double bond at position 1 and a triple bond at position 4.
4. **Draw the structure**: Place a double bond between carbon atoms 1 and 2, and a triple bond between carbon atoms 4 and 5. Fill the remaining valences with hydrogen atoms.
**Structure**:
```
H H
| |
H==C--C--C--C≡C--H
| |
H H
```
### (iv) Pent-1-en-3-yne
1. **Identify the main chain**: The prefix "pent-" indicates that there are 5 carbon atoms in the main chain.
2. **Number the carbon chain**: Number the carbon atoms from one end to the other. We can start from the left:
- 1, 2, 3, 4, 5.
3. **Identify the positions of the double and triple bonds**: The name indicates a double bond at position 1 and a triple bond at position 3.
4. **Draw the structure**: Place a double bond between carbon atoms 1 and 2, and a triple bond between carbon atoms 3 and 4. Fill the remaining valences with hydrogen atoms.
**Structure**:
```
H H
| |
H==C--C≡C--C--C--H
| |
H H
```
