Periodicproperties show aregular gradation onmovingfrom leftto rightin aperiodor fromtoptobottomin a group . Downa groupthe atomicionicradii, metalliccharacterand reducing characterincreasewhileionizationenthalpyand electronegativitydecrease. Alonga periodfrom leftto rightatomic ionicradiiand metalliccharacterdecrease whileionizationenthalpyelectronegativitynon- metalliccharacterand oxidisingpowerincreases. However ,electrongainenthalpybecomesless negativedown agroupbut morenegativealonga period. Incontrastinertgaseshavepositiveelectrongainenthalpies whichdo not showanyregular trend .The incorrectstatementamong thefollowingis :

Periodicproperties show aregular gradation onmovingfrom leftto rightin

1.	Periodicproperties show aregular gradation onmovingfrom leftto rightin aperiodor fromtoptobottomin a group . Downa groupthe atomicionicradii, metalliccharacterand reducing characterincreasewhileionizationenthalpyand electronegativitydecrease. Alonga periodfrom leftto rightatomic ionicradiiand metalliccharacterdecrease whileionizationenthalpyelectronegativitynon- metalliccharacterand oxidisingpowerincreases. However ,electrongainenthalpybecomesless negativedown agroupbut morenegativealonga period. Incontrastinertgaseshavepositiveelectrongainenthalpies whichdo not showanyregular trend .The incorrectstatementamong thefollowingis :
Answer» The firstionizationpotentialof A1 islessthanthefirstionizationpotential of Mg. The secondionizationpotential of Mg isgreaterthan thesecondionizationpotentialof NA . The firstionizationpotentialof Na isless than the firstionizationpotentialof mg Thethirdionizationpotentialof Mg isgreaterthan thethirdionizationpotentialof A1. Solution :`Delta_(i)H_(2)` of Na ishigherthan THATOF Mg becausein CASEOF Na thesecondelectronhas toberemovedfrom thenoblegas corewhile in case ofMg, REMOVALOF secondelectrongivesa nobegas core.