Basic is related to Iron. Iron is part of Molecule. you are likely to find Molecule in/at/on Substance. 
Widespread is the opposite of Limited. Limited is a synonym of Express. Express is related to Speed. 
Basic <--RelatedTo--> Iron --PartOf--> Molecule --AtLocation--> Substance 
Widespread <--Antonym--> Limited <--Synonym--> Express <--RelatedTo--> Speed 