When acetone is treated with excess of bezaldehyde in the presence of base, the crossed condensation add two equivalents of benzaldehyde and expets two equivalent of water and forms [x]. Identify the structure of [X] when [X] reacts with `NH_(2)OH` how many stereoisomers are formed .

Explanation

To solve the problem step by step, we will identify the structure of compound [X] formed from the reaction of acetone and benzaldehyde, and then determine how many stereoisomers are produced when [X] reacts with hydroxylamine (NH₂OH).

### Step 1: Write the Reaction
When acetone (CH₃COCH₃) is treated with excess benzaldehyde (C₆H₅CHO) in the presence of a base, a crossed aldol condensation occurs. The reaction can be represented as follows:

\[ \text{Acetone} + \text{Benzaldehyde} \xrightarrow{\text{Base}} [X] + \text{2 H}_2\text{O} \]

### Step 2: Identify the Structure of [X]
In the reaction, benzaldehyde is in excess, which means it will react with both carbonyl groups of acetone. The product [X] can be derived from the aldol condensation of acetone and benzaldehyde. The structure of [X] can be drawn as follows:

1. **Condensation of Acetone and Benzaldehyde**:
- The first step involves the formation of a β-hydroxy ketone.
- The second step involves dehydration to form an α,β-unsaturated carbonyl compound.

The structure of [X] can be represented as:

\[ \text{Ph-CH=CH-C(=O)-CH(Ph)-CH}_3 \]

Where "Ph" denotes the phenyl group (C₆H₅).

### Step 3: React [X] with NH₂OH
When [X] reacts with hydroxylamine (NH₂OH), it forms oxime derivatives. The reaction can lead to the formation of stereoisomers due to the presence of double bonds in the structure of [X].

### Step 4: Determine the Number of Stereoisomers
The compound [X] has two double bonds, which can give rise to geometrical (cis/trans) isomerism.

1. **Identify Double Bonds**:
- The double bonds in [X] allow for cis and trans configurations.

2. **Count Possible Configurations**:
- For each double bond, there are two configurations (cis and trans).
- Since there are two double bonds, the total number of stereoisomers can be calculated as \(2^n\), where \(n\) is the number of double bonds that can exhibit geometrical isomerism.

Thus, for [X], the number of stereoisomers is:

\[ 2^2 = 4 \text{ stereoisomers} \]

### Final Answer
The structure of [X] is an α,β-unsaturated carbonyl compound formed from the reaction of acetone and benzaldehyde. When [X] reacts with hydroxylamine, it produces **4 stereoisomers**.