Group is related to Organization. Organization is related to Organ. Organ is related to Musical. 
Iron entails/necessarily involves Heat. Heat is related to Boil. Boil is the opposite of Freeze. 
Group <--RelatedTo--> Organization <--RelatedTo--> Organ <--RelatedTo--> Musical 
Iron --Entails--> Heat <--RelatedTo--> Boil <--Antonym--> Freeze 