Explanation:

Molecular formula: C5H10O2

To determine the number of ester isomers possible for a compound with the given molecular formula, we need to consider the different ways the atoms can be arranged.

Step 1: Identifying the functional group
The given molecular formula contains the elements carbon (C), hydrogen (H), and oxygen (O). Since it is an ester, the functional group is a carbonyl group (C=O) attached to an oxygen atom (O).

Step 2: Determining the possible carbon chain arrangements
The molecular formula C5H10O2 indicates that there are 5 carbon atoms in the compound. To determine the possible carbon chain arrangements, we can consider the different isomers of pentane (C5H12) and subtract 2 hydrogen atoms for each oxygen atom in the ester group.

The possible carbon chain arrangements for the given molecular formula are as follows:

1. Straight chain pentyl ester: CH3(CH2)3COOCH3
2. Branched chain pentyl ester: CH3(CH2)2CH(CH3)COOCH3

Step 3: Determining the possible ester isomers
To determine the different possible isomers, we need to consider the different ways the remaining atoms (hydrogen and oxygen) can be arranged around the carbon chain.

Key points:
- The ester group consists of a carbon atom (C) double-bonded to an oxygen atom (O) and single-bonded to another oxygen atom (O).
- The remaining carbon atoms in the carbon chain can form different isomers by branching or remaining in a straight chain.

Calculating the number of isomers:
1. For the straight chain pentyl ester (1 isomer), the remaining carbon atoms can be arranged in 4 different ways.
2. For the branched chain pentyl ester (1 isomer), the remaining carbon atoms can be arranged in 5 different ways.

Therefore, the total number of ester isomers possible for the given molecular formula C5H10O2 is 1 + 4 + 1 + 5 = 11.

However, we need to consider the constraints of the molecular formula. The given molecular formula indicates that there are 10 hydrogen atoms and 2 oxygen atoms. Since each ester group contains 2 oxygen atoms, we need to subtract 2 from the total number of isomers.

Therefore, the correct number of ester isomers possible for the compound with molecular formula C5H10O2 is 11 - 2 = 9.