Stability of the species Li₂, $$Li_2^−$$ and $$Li_2^+$$ increases in the order of:

Which one of the following molecules is expected to exhibit diamagnetic behaviour?

The first ionization potential of Na is 5.1 eV. The value of electron gain enthalpy of Na+ will be:

Which of the following represents the correct order of increasing first ionization enthalpy for Ca, Ba, S, Se and Ar?