Question

a. Li, Si, He, , Na,P Which of these
elements belong to be period 3?​

Answer 1

Answer:

SI- silicon because in first period their are two elements Hydrogen and Helium

and in second period their are 8 elements- Li,be,b,c,n,o,f,ne

and in third period their are also 8 elements- na,mg,al,Si,p,s,cl,ar

Answer 2

Answer:

k,li,na,be which of these atoms has smallest atomic radius ?