An element with Z = 18  belongs to ………period of modern periodic table

detailed solution

Correct option is A

Hints to predict the position of element in the Modern periodic table :1)Elements from Z = 58-71……Lanthanoids…..4f series….6th period……3rd(IIIB) group;2)Elements from Z = 90-103……Actinoids…..5f series….7th period……3rd(IIIB) group;3)Elements from Z = 104-118………..Last two digits gives group number….. 7th period;4)Elements from Z = 31-57….subtract 18 to get preceding element;5)Elements from Z = 72-89….subtract 32 to get preceding element;6)Elements from Z = 104-120….subtract 32 to get preceding element ;For Z=104-120….simplest Hint7)Elements from Z = 104-120….subtract 82 to get a lower member(Z<30) belonging to same group;Hints 4, 5 and 6 can be used repeatedly until an element belonging to same group with Z < 30 is obtained;Elements with Z < 30 with their group, period and block can be known from Electronic configuration;Ex : Z=118, 86, 54, 36, 18, 10….belong to 18th(zero) group;(118-32)=86; (86-32)=54; (54-18)=36; (36-18)=18;(18-8)=10:Z = 10…….Ne…2s22p6….…n=2….2nd period……p-block….…..18th group;Z = 18…….Ar….3s23p6….…n=3….3rd period……p-block……...18th group;Z = 36…….Kr….4s24p6…….n=4….4th period……p-block…..….18th group;Z = 54……..Xe…5s25p6…….n=5….5th period……p-block..……18th group;Z = 86…….Rn….6s26p6…….n=6….6th period……p-block….….18th group;Z = 118……Og…7s27p6….…n=7….7th period……p-block….….18th group;