N2 and NO+ both are diamagnetic substances. — Chemical Bonding Chemistry Question

💡 Solution & Explanation

Step 1: The enthalpy of fusion represents the energy required to melt a solid. Stronger intermolecular forces lead to a higher melting point and higher enthalpy of fusion. Step 2: Helium is a monoatomic noble gas with the weakest London dispersion forces among all elements due to its extremely small size and extremely low polarizability. Step 3: Therefore, Helium has the lowest enthalpy of fusion among the choices, matching option (d).