JEE MainChemistryChemical Bonding and Molecular Structure
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R) . Assertion (A) : The first ionization enthalpy of N₂ is greater than that of the N atom, whereas the first ionization enthalpy of O₂ is lower than that of the O atom. Reason (R) : The electron removed during the ionization of N₂ comes from a bonding molecular orbital, while for O₂ , it comes from an antibonding
Options
- ABoth (A) and (R) are true but (R) is NOT the correct explanation of (A)
- B(A) is true but (R) is false
- CBoth (A) and (R) are true and (R) is the correct explanation of (A)
- D(A) is false but (R) is true
Correct answer
C. Both (A) and (R) are true and (R) is the correct explanation of (A)
Step-by-step solution
According to Molecular Orbital Theory, the energy of a bonding molecular orbital is lower than that of the constituent atomic orbitals, while the energy of an antibonding molecular orbital is higher. For N₂ (14 electrons), the highest occupied molecular orbital (HOMO) is the bonding _ 2p_z orbital. Since this orbital is lower in energy and more stable than the isolated 2p atomic orbitals of nitrogen, more energy is required to remove an electron from N₂ than from an isolated N atom. Thus, the first ionization entha