Which of the following statements is/are correct about the drawback of octet theory?
I. This theory does not account for the shape of molecules.
II. It does not explain the relative stability.

Correct option is D

The correct answer is (d) Both I and II.
The octet theory, which was proposed to explain chemical bonding, has certain limitations or drawbacks:
1. Statement I: This theory does not account for the shape of molecules. This statement is correct. The octet theory only focuses on the arrangement of electrons to achieve a stable configuration of eight electrons in the outer shell. However, it does not provide any insight into the actual three-dimensional shape of molecules. For instance, it cannot explain the shapes of molecules like methane (tetrahedral) or water (bent).
2. Statement II: It does not explain the relative stability. This statement is also correct. The octet theory does not address why certain compounds are more stable than others. It does not provide a quantitative measure of stability or explain factors such as bond strength or energy considerations, which are essential for understanding molecular stability.
Information Booster: ● Octet theory was an early attempt to explain chemical bonding, focusing on achieving noble gas configurations. ● The theory works well for simple ionic and covalent compounds but fails to explain more complex molecules. ● Advanced theories, such as the VSEPR theory and molecular orbital theory, were developed to address these limitations. ● Octet theory also does not explain the presence of molecules with expanded or incomplete octets, such as phosphorus pentachloride (PCl5) and boron trifluoride (BF3).