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

Which one of the following represents the correct order of increasing

1.	Which one of the following represents the correct order of increasing first ionization enthalpy of Ca, Ba, S, Se and Ar ?
Answer» `Ca ltSlt Ba lt Ase lt Ar` `S lt Se lt Ca lt Ba lt Ar` `Ba lt Ca lt Se lt S lt Ar` `Ca lt Ba lt S lt Se lt Ar` Solution :`Ba lt Ca lt Se lt S lt Ar` `{:("Period"3^(rd),16^(S),18^(Ar)),("Period"4^(TH),20^(Ca),34^(Se)),("Period"6^(th),56^(Ba),):}` First ionization potentials increases in a period with increasing of atomic number `:.{:((i)Delta_(i)H(Ar)gt Delta_(i)H_(i)(S)),((ii)Delta_(i)H(Se)gt Delta_(i)H(Ca)):}}....(x) ` And in a group first ionization enthalpy DECREASES from top to BOTTOM `:.{:((i)Delta_(i)H(Ba)lt Delta_(i)H(Ca)),((ii)Delta_(i)H(Se)lt Delta_(i)H(S)):}}....(y) ` From (x)and (y) we can SAY that order of first ionization potential is as `Ba lt Ca lt Se lt S lt Ar`