In whichof the followingoptionsthe order ofarrangementdoes notagreewith thevariationof property inindicated against it ?

In whichof the followingoptionsthe order ofarrangementdoes notagreewit

1.	In whichof the followingoptionsthe order ofarrangementdoes notagreewith thevariationof property inindicated against it ?
Answer» `I lt Na lt C1 lt F` (increasingelectrongain enthalpy) `Li lt Na lt K lt Rb` (increasingmetallicradius ) `A1^(3+) lt Mg^(2+) lt Na^(+) lt F^(-)` (inreasingionic SIZE ) `B lt C lt N lt O` (inreasingfirstionisationenthalpy ) Solution :Theelectrongainenthalpyof C1 ismorenegativethan thatof F i.e.,negativeelectrongain enthalpyincreases`I lt Br gt f lt C1` .Thusoption ( a) iswrong Ionizationenergiesof alkalimetalsdecreasesandhencetheirmetalliccharacterincreasesdown thegroup (i.e., `Li lt Ne lt K lt Rb)` Thusoption( b)is correct. Amongisoelectronicions,ionicsize increase asthe + ve chargedecreasesor the - vechargeincreases `(i.e., A1^(3+) lt Mg^(2+) lt Na^(+) lt F^(-))` Thusoption (c ) is correct. Ingeneralalong aperiod, firstionizationenergyincrease from leftto rightas thenuclearcharge increases. Butdue togreaterstabilityof half- filledE.C. of N , itsionizationenergyis higherthant thatof O.Thusthe actualorder is `B lt C lt O lt N` i.e.,OPTION (d ) isalsowrong.