Arrange these species in the order of increasing size: (i) Ar, Cl- , K+ , S2-, Ca2+
(ii) Fe, Fe2+, Fe+
(iii) Na, Rb, K
(iv) N, C, O, B, F

Just Note the below follow the below principle

#1

#2

#3

#4

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

i think its 100

i hope this !