Identify (Z)-2-pentene :

Options

A.
B.
C.
D.

Answer

To identify (Z)-2-pentene, we will follow these steps:

### Step 1: Understand the Structure of 2-Pentene
2-Pentene is an alkene with the molecular formula C5H10. The double bond is located between the second and third carbon atoms in the chain. The structure can be represented as:
```
CH3-CH=CH-CH2-CH3
```

### Step 2: Identify the Groups Attached to the Double Bond
In 2-pentene, the double bond connects the second and third carbon atoms. We need to identify the groups attached to these carbons:
- **C2** (the second carbon) has:
- CH3 (methyl group)
- H (hydrogen atom)

- **C3** (the third carbon) has:
- CH2 (part of the ethyl group)
- CH3 (methyl group)

### Step 3: Assign Priorities to the Groups
According to the Cahn-Ingold-Prelog priority rules, we assign priorities based on the atomic number of the atoms directly attached to the double-bonded carbons:
- For C2:
- CH3 (C) has a higher priority than H (H).

- For C3:
- CH3 (C) has a higher priority than CH2 (C).

### Step 4: Determine the Configuration (Z or E)
- If the higher priority groups on each carbon are on the same side of the double bond, the configuration is Z (from the German "zusammen," meaning together).
- If they are on opposite sides, the configuration is E (from the German "entgegen," meaning opposite).

In (Z)-2-pentene, both higher priority groups (CH3 from C2 and CH3 from C3) are on the same side of the double bond.

### Step 5: Write the Final Structure
Thus, the structure of (Z)-2-pentene can be represented as:
```
CH3
|
CH3-CH=CH-CH2-CH3
```
Where the CH3 groups are on the same side of the double bond.

### Conclusion
Therefore, (Z)-2-pentene is identified as the compound where the higher priority groups are on the same side of the double bond.

---