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 .Itthe ionicradiiof K^(+)and F^(-) are about1.34 Å eachthen theexpectedvaluesof atomicradii ofK and Fshouldbe respectively :

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 .Itthe ionicradiiof K^(+)and F^(-) are about1.34 Å eachthen theexpectedvaluesof atomicradii ofK and Fshouldbe respectively :
Answer» 2.31 and 0.64 `Å` 2.31 and1.34 `Å` `0.64 and 2.31 `Å` `1.34 and 1.34 `Å` Solution :Sincethe size of K islargerthan `K^(+) (1.34 Å )` ANDTHAT of F is smallerthan thatof `F^(-)`(1.34 Å ) , thereforeoption (a) is CORRECT.