Assertion Helium shows only positive deviation from ideal behaviour at room temp

Assertion is correct: Helium shows positive deviation from ideal gas behavior at room temperature because its molecules are small and have very weak intermolecular attractions, causing repulsive forces (due to finite volume) to dominate. Reason is also correct: Helium is an inert gas. However, the inertness is not the direct cause of the positive deviation; the deviation arises from the gas's physical properties (small size, weak forces), not chemical inertness. Thus, the reason is not the correct explanation for the assertion.