Heat of combustion of two isomer x and y are 17 kJ/mol and 12 kJ/mol respectively. From this information it may be concluded that :

Options

A. isomer x is 5 kJ/mol more stable
B. isomer y is 5 kJ/mol less stable
C. isomer y has 5 kJ/mol more potential energy
D. isomer x is 5 kJ/mol less stable

Explanation

To solve the problem regarding the heat of combustion of isomers X and Y, we can follow these steps:

### Step 1: Understand the Concept of Heat of Combustion
The heat of combustion is the amount of energy released when a substance is burned in the presence of oxygen. It is an indicator of the stability of the compound: the higher the heat of combustion, the less stable the compound is.

### Step 2: Analyze the Given Data
We have:
- Heat of combustion of isomer X = 17 kJ/mol
- Heat of combustion of isomer Y = 12 kJ/mol

### Step 3: Compare the Heats of Combustion
Since the heat of combustion of X (17 kJ/mol) is greater than that of Y (12 kJ/mol), we can conclude that:
- Isomer X is less stable than isomer Y.

### Step 4: Determine the Stability Difference
To find out how much more stable Y is compared to X, we subtract the heat of combustion of Y from that of X:
- Stability difference = Heat of combustion of X - Heat of combustion of Y
- Stability difference = 17 kJ/mol - 12 kJ/mol = 5 kJ/mol

### Step 5: Conclude the Stability Relationship
From the calculations, we conclude that:
- Isomer Y is 5 kJ/mol more stable than isomer X.
- Conversely, isomer X is 5 kJ/mol less stable than isomer Y.

### Step 6: Evaluate the Options
Now we can evaluate the provided options:
1. Isomer X is 5 kJ/mol more stable - **Incorrect**
2. Isomer Y is 5 kJ/mol less stable - **Incorrect**
3. Isomer Y has 5 kJ/mol more potential energy - **Incorrect**
4. Isomer X is 5 kJ/mol less stable - **Correct**

### Final Answer
The correct conclusion is that isomer X is 5 kJ/mol less stable than isomer Y.

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