The possible number of stereoisomers of the product of following reaction would be:
`Ph-CH=CH-underset(CH_3)underset(|)(CH)-CHOoverset(NH_2OH)rarr`

Answer

To determine the possible number of stereoisomers for the product of the given reaction, we will follow these steps:

### Step 1: Identify the Product
The reaction involves the compound `Ph-CH=CH-CH(CH3)-CHO` reacting with hydroxylamine (NH2OH). The product formed will have a double bond and a chiral center due to the presence of the aldehyde group.

### Step 2: Analyze the Structure
The product can be represented as:
- `Ph-CH=CH-CH(CH3)-C(=NOH)-H`
This structure contains:
- A double bond between the two carbon atoms adjacent to the phenyl group.
- A chiral center at the carbon that is bonded to the hydroxylamine and the methyl group.

### Step 3: Count the Pi Bonds
In the product, we have:
- One double bond between the two carbon atoms (C=C).
- One double bond between the carbon and the nitrogen (C=N).
Thus, there are **2 pi bonds** in total.

### Step 4: Identify Chiral Centers
A chiral center is a carbon atom that has four different groups attached to it. In our product:
- The carbon atom bonded to the hydroxylamine (C=N) is a chiral center because it is attached to:
1. The phenyl group (Ph)
2. The hydrogen atom (H)
3. The methyl group (CH3)
4. The carbon atom of the double bond (C=C)

Thus, there is **1 chiral center** in the product.

### Step 5: Calculate the Total Number of Stereoisomers
The formula to calculate the number of stereoisomers is:
\[ \text{Number of stereoisomers} = 2^n \]
where \( n \) is the sum of the number of pi bonds involved in geometrical isomerism and the number of chiral centers.

From our analysis:
- Number of pi bonds (involved in geometrical isomerism) = 2
- Number of chiral centers = 1

Thus, \( n = 2 + 1 = 3 \).

Now, applying the formula:
\[ \text{Number of stereoisomers} = 2^3 = 8 \]

### Final Answer
The possible number of stereoisomers of the product of the reaction is **8**.

---