Which of the following statement are true?

Options

A. `2`-Butanone on reaction with `2,4-DNP` forms two compounds which are geometrical isomers and can be separated.
B. Acetophenone on reaction with `HCN` forms two compounds which are geometrical isomers.
C. Acetone on reaction with `NH_(3)` forms two compounds which are resolvable.
D. Acetaldehyde on reaction with `NH_(2)OH` forms two compounds which have different melting points.

Explanation

To determine which statements are true regarding the reactions of various compounds, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement A: Two butanone on reactions forms geometrical isomers.**
- **Analysis**: 2-butanone can react with 2,4-DNP (dinitrophenyl hydrazine) to form a hydrazone. The presence of a carbonyl group (C=O) allows for the formation of geometrical isomers due to the possibility of different spatial arrangements around the double bond. Thus, this statement is **true**.

2. **Statement B: Acetophenone on reaction with HCN forms two compounds which are geometrical isomers.**
- **Analysis**: When acetophenone reacts with HCN, it forms a cyanohydrin. This compound does not exhibit geometrical isomerism because it does not have a double bond or a suitable substituent arrangement to allow for cis-trans isomerism. Instead, it can exhibit optical isomerism due to the formation of a chiral center. Therefore, this statement is **false**.

3. **Statement C: Acetone on reaction with NH3 forms two compounds which are dissolvable.**
- **Analysis**: Acetone reacts with ammonia to form an imine. However, this reaction typically leads to the formation of a single compound rather than two distinct compounds. Additionally, the resulting compound is not chiral and does not exhibit enantiomerism. Thus, this statement is **false**.

4. **Statement D: Acetaldehyde on reaction with NH2OH forms two compounds which have different melting points.**
- **Analysis**: Acetaldehyde reacts with hydroxylamine (NH2OH) to form an oxime. Oximes can exist in two geometrical isomers (E and Z forms) due to the presence of a double bond between the nitrogen and carbon. These isomers have different physical properties, including melting points. Therefore, this statement is **true**.

### Conclusion:
The true statements are **A and D**.