X, J, Z, B, Q and D are the elements belonging to 18th group of Modern periodic table. The correct trend of ionisation potenial in these elements is X > J > Z > B > Q > D. The element ‘X’ in the sequence is
Atomic radius….He<Ne<Ar<Kr<Xe;
Density ….He<Ne<Ar<Kr<Xe<Rn;
IP ….He>Ne>Ar>Kr>Xe>Rn;
Positive electron gain enthalpy ….Ne>Ar=Kr>Xe>Rn>He;Due to stable configuration
MP and BP…..He<Ne<Ar<Kr<Xe<Rn; Due to incease in the strength of Vanderwaals attractions
Abundance in atmosphere(by volume)…..Ar>Ne>He>Kr>Xe;