The given compound C5H8O can have different isomers based on the arrangement of atoms. The reaction with 2, 4-dinitrophenyl hydrazine (2, 4-DNPH) results in the formation of an orange precipitate, indicating the presence of a carbonyl group.

Let us analyze the different possible isomers of C5H8O:

1. Straight chain aldehyde (pentanal): It contains the carbonyl group at the end of the carbon chain.

2. Straight chain ketone (2-pentanone): It contains the carbonyl group in the middle of the carbon chain.

3. Branched chain aldehyde (2-methylbutanal): It contains a methyl group attached to the second carbon of the chain, where the carbonyl group is present.

4. Branched chain ketone (3-methyl-2-butanone): It contains a methyl group attached to the second carbon of the chain, where the carbonyl group is present.

5. Cycloalkane with a carbonyl group (cyclopentanone): It contains a carbonyl group within a cyclic structure.

6. Alkene with a carbonyl group (2-penten-1-one): It contains a double bond and a carbonyl group.

7. Alkyne with a carbonyl group (2-pentyne-2-one): It contains a triple bond and a carbonyl group.

8. Ether with a carbonyl group (2-methoxy-2-pentanone): It contains an ether group (-O-) and a carbonyl group.

9. Cyclic ether with a carbonyl group (2-cyclopentyl-2-oxopropane): It contains a cyclic ether group (-O-) and a carbonyl group.

All these isomers can react with 2, 4-DNPH to form an orange precipitate. Therefore, the correct answer is 9 different isomers of C5H8O that give an orange precipitate with 2, 4-DNPH.