Only is a synonym of Alone. Alone is related to Individual. Individual is the opposite of Nation. Nation is the opposite of State. 
Scientific is related to Experiment. Experiment is related to Observation. 
Only <--Synonym--> Alone <--RelatedTo--> Individual <--Antonym--> Nation <--Antonym--> State 
Scientific <--RelatedTo--> Experiment <--RelatedTo--> Observation 