Which are not position isomers?

Options

A. `CH_(3)-underset(CH_(3))underset("| ")"CH"-underset(CH_(3))underset("| ")"CH"-CH_(3) and CH_(3)-overset(CH_(3))overset("| ")underset(CH_(3))underset("| ")"C "-CH_(2)-CH_(3)`
B. `CH_(3)-underset(H)underset(|)CH-CH_(2)-underset(Cl)underset(|)C=O and CH_(3)-underset(Cl)underset(|)CH-CH_(2)-underset(H)underset(|)C=O`
C.
D.

Answer

To determine which compounds are not position isomers, we need to understand what position isomers are. Position isomers are compounds that have the same molecular formula and the same carbon skeleton (main chain), but differ in the position of a functional group or substituent on that skeleton.

### Step-by-Step Solution:

1. **Identify the Compounds**: Start by listing the compounds you are analyzing. For example, let's say we have the following compounds:
- Compound A: CH3-CH2-CH(CH3)-OH
- Compound B: CH3-CH(CH3)-CH2-OH
- Compound C: CH3-CO-CH2-CHO
- Compound D: CH3-CH2-CH2-CHO

2. **Check the Main Chain**: For each compound, identify the main carbon chain. The main chain is the longest continuous chain of carbon atoms.
- For Compound A: The main chain is 3 carbons (C1, C2, C3).
- For Compound B: The main chain is also 3 carbons (C1, C2, C3).
- For Compound C: The main chain is 3 carbons (C1, C2, C3).
- For Compound D: The main chain is 4 carbons (C1, C2, C3, C4).

3. **Identify the Functional Groups**: Look at the functional groups or substituents attached to the main chain.
- Compound A has an -OH group on the third carbon.
- Compound B has an -OH group on the second carbon.
- Compound C has a carbonyl (C=O) and an aldehyde (CHO) group.
- Compound D has an aldehyde (CHO) group at the end of the chain.

4. **Determine Position Isomers**: Now, check if the compounds are position isomers by comparing the positions of the functional groups.
- Compounds A and B are position isomers because they have the same main chain and differ in the position of the -OH group.
- Compound C and D are not position isomers of A and B because they have different functional groups (C=O and CHO) and hence are functional isomers.

5. **Conclusion**: Based on the analysis, the compounds that are not position isomers are Compound C and Compound D, as they differ in functional groups and do not have the same main chain structure as A and B.

### Final Answer:
The compounds that are not position isomers are Compound C (CH3-CO-CH2-CHO) and Compound D (CH3-CH2-CH2-CHO).