Explain the following data :
Ionisation energy `Cl lt H lt O lt N lt F` .

The ionization potential values of an element are in the following order I_(1) lt I_(2) lt lt lt lt I_(3) lt I_(4) lt I_(5) . The element is

Find the total number of correct orders among the following. (a) Order of electron affinity : S gt O^(-) (b) Order of ionic radius: AI^(3+) lt Mg^(2+) lt O^(2-) (c) Order of electronegativity: Si lt P lt C lt N (d) Order of atomic radius: O lt C lt S lt Se (e) Order of second ionization energy: C lt N lt F lt O (f) Order of ionic radii : S^(2-) lt CI^(-) lt K^(+) lt Ca^(2+)

Which of the following is(are) correct for if atom ? 1s lt 2s lt 2p lt 3s lt 3p 1s lt 2s = 2p lt 3s = 3p 1s lt 2p lt 3d lt 4s 1s lt 2s lt 4s lt 3d The correct choice is

Among the second period elements the actual ionisation enthalpies are in the order Li lt B lt Be lt C lt O lt N lt F lt Ne . Explain why? O has lower (Delta_iH)_1 than N and F ?