An alkene ‘A’ on ozonolysis gives a mixture of ethanal and pentan-3-one. Write structure and IUPAC name of ‘A’.

Explanation

To determine the structure and IUPAC name of the alkene 'A' that gives a mixture of ethanal and pentan-3-one upon ozonolysis, we can follow these steps:

### Step 1: Understand the Products of Ozonolysis
Ozonolysis of alkenes typically breaks the double bond and forms carbonyl compounds (aldehydes or ketones). In this case, we have:
- Ethanal (acetaldehyde) - CH3CHO
- Pentan-3-one - CH3COCH2CH2CH3

### Step 2: Analyze the Products
From the products, we can deduce that:
- Ethanal (C2H4O) indicates that one of the fragments must contain two carbon atoms.
- Pentan-3-one (C5H10O) indicates that the other fragment must contain five carbon atoms.

### Step 3: Determine the Structure of Alkene 'A'
To find the alkene 'A', we need to consider how these products could be formed from a single alkene through ozonolysis.

1. The carbon skeleton of pentan-3-one suggests that the alkene must have a structure that, when cleaved, can yield a 3-carbon fragment and a 2-carbon fragment.
2. The simplest way to achieve this is to consider an alkene that has a double bond between the second and third carbon atoms of a five-carbon chain.

### Step 4: Construct the Alkene
Let's construct the alkene 'A':
- If we take 2-pentene (CH3-CH=CH-CH2-CH3) as our alkene, ozonolysis would break the double bond between the second and third carbon atoms.
- This would yield:
- Ethanal from the terminal carbon (CH3-CHO)
- Pentan-3-one from the remaining carbon chain (CH3-CO-CH2-CH2-CH3)

### Step 5: Write the Structure and IUPAC Name
The structure of alkene 'A' (2-pentene) can be represented as follows:

```
H H
\ /
C
/ \
H3C--C C--CH2--CH3
\ /
C
/ \
H H
```

The IUPAC name of 'A' is **2-pentene**.

### Summary
The alkene 'A' that gives ethanal and pentan-3-one upon ozonolysis is 2-pentene.

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