How many of the following compounds give `1^(@)` alcohol with Grignard reagent `(CH_(3) MgBr)` is :
Acetaldehyde, Formaldehyde, Ethylethanoate, Acetone, Oxirane, Acetyl chloride, Acetamide, Carbon dioxide, Methyl methanoate.

Explanation

To determine how many of the given compounds yield a primary alcohol when reacted with the Grignard reagent (CH₃MgBr), we will analyze each compound step by step.

### Step-by-Step Solution:

1. **Acetaldehyde (CH₃CHO)**:
- Acetaldehyde reacts with CH₃MgBr. The nucleophile (CH₃⁻) attacks the carbonyl carbon (C=O), leading to the formation of a secondary alcohol after hydrolysis.
- **Result**: Does not give a primary alcohol.

2. **Formaldehyde (HCHO)**:
- Formaldehyde reacts with CH₃MgBr. The nucleophile attacks the carbonyl carbon, resulting in the formation of a primary alcohol (ethanol) after hydrolysis.
- **Result**: Gives a primary alcohol.

3. **Ethyl Ethanoate (C₂H₅COOCH₃)**:
- Ethyl ethanoate reacts with CH₃MgBr. The nucleophile attacks the carbonyl carbon, leading to the formation of a tertiary alcohol after two reactions with the Grignard reagent.
- **Result**: Does not give a primary alcohol.

4. **Acetone (CH₃COCH₃)**:
- Acetone reacts with CH₃MgBr. The nucleophile attacks the carbonyl carbon, resulting in the formation of a tertiary alcohol after hydrolysis.
- **Result**: Does not give a primary alcohol.

5. **Oxirane (C₂H₄O)**:
- Oxirane (an epoxide) reacts with CH₃MgBr. The nucleophile attacks the less hindered carbon, leading to the formation of a primary alcohol after hydrolysis.
- **Result**: Gives a primary alcohol.

6. **Acetyl Chloride (CH₃COCl)**:
- Acetyl chloride reacts with CH₃MgBr. The nucleophile attacks the carbonyl carbon, leading to the formation of a tertiary alcohol after hydrolysis.
- **Result**: Does not give a primary alcohol.

7. **Acetamide (CH₃CONH₂)**:
- Acetamide reacts with CH₃MgBr. The nucleophile attacks the carbonyl carbon, but the reaction leads to the formation of methane (CH₄) instead of an alcohol.
- **Result**: Does not give a primary alcohol.

8. **Carbon Dioxide (CO₂)**:
- Carbon dioxide reacts with CH₃MgBr to form a carboxylic acid (after hydrolysis), not an alcohol.
- **Result**: Does not give a primary alcohol.

9. **Methyl Methanoate (HCOOCH₃)**:
- Methyl methanoate reacts with CH₃MgBr. The nucleophile attacks the carbonyl carbon, leading to the formation of acetaldehyde (which is a secondary alcohol) after hydrolysis.
- **Result**: Does not give a primary alcohol.

### Summary of Results:
- Compounds that give primary alcohol: **Formaldehyde** and **Oxirane**.
- Total count of compounds giving primary alcohol: **2**.

### Final Answer:
**2**