How many of following cannot show tautomerism acetophenone, acetaldehyde, cyclohexanone, acetylacetone, benzoquinone, acetone, benzaldehyde, butanone, ethyl acetoacetate

Explanation

To determine how many of the given compounds cannot show tautomerism, we need to analyze each compound based on the presence of alpha hydrogen atoms. Tautomerism typically occurs in aldehydes and ketones that have at least one alpha hydrogen atom.

### Step-by-Step Solution:

1. **Acetophenone (C6H5COCH3)**:
- Structure: Contains a phenyl group (C6H5) and a carbonyl group (C=O) attached to a methyl group (CH3).
- Alpha Hydrogen: Yes, there are alpha hydrogens on the methyl group.
- **Conclusion**: Can show tautomerism.

2. **Acetaldehyde (CH3CHO)**:
- Structure: Contains a carbonyl group (C=O) attached to a methyl group (CH3).
- Alpha Hydrogen: Yes, there is one alpha hydrogen on the methyl group.
- **Conclusion**: Can show tautomerism.

3. **Cyclohexanone (C6H10O)**:
- Structure: A cyclic ketone with a carbonyl group.
- Alpha Hydrogen: Yes, there are alpha hydrogens on the carbons adjacent to the carbonyl.
- **Conclusion**: Can show tautomerism.

4. **Acetylacetone (CH3COCH2COCH3)**:
- Structure: Contains two carbonyl groups and a methylene group in between.
- Alpha Hydrogen: Yes, there are alpha hydrogens on the methylene group.
- **Conclusion**: Can show tautomerism.

5. **Benzoquinone (C6H4O2)**:
- Structure: Contains two carbonyl groups in a cyclic structure.
- Alpha Hydrogen: No, there are no alpha hydrogens present.
- **Conclusion**: Cannot show tautomerism.

6. **Acetone (CH3COCH3)**:
- Structure: A simple ketone with two methyl groups.
- Alpha Hydrogen: Yes, there are alpha hydrogens on both methyl groups.
- **Conclusion**: Can show tautomerism.

7. **Benzaldehyde (C6H5CHO)**:
- Structure: Contains a carbonyl group attached to a phenyl group.
- Alpha Hydrogen: No, there are no alpha hydrogens present.
- **Conclusion**: Cannot show tautomerism.

8. **Butanone (C4H8O)**:
- Structure: A ketone with two methyl groups and one ethyl group.
- Alpha Hydrogen: Yes, there are alpha hydrogens on the methyl groups.
- **Conclusion**: Can show tautomerism.

9. **Ethyl Acetoacetate (CH3COCH2COOEt)**:
- Structure: Contains two carbonyl groups with an ethyl ester.
- Alpha Hydrogen: Yes, there are alpha hydrogens on the methylene group.
- **Conclusion**: Can show tautomerism.

### Summary of Results:
- Compounds that can show tautomerism: Acetophenone, Acetaldehyde, Cyclohexanone, Acetylacetone, Acetone, Butanone, Ethyl Acetoacetate.
- Compounds that cannot show tautomerism: Benzoquinone, Benzaldehyde.

### Final Answer:
**Total number of compounds that cannot show tautomerism: 2 (Benzoquinone and Benzaldehyde)**.