Question: Which excipient has the highest refractive index?
Paraphrase: State the substrate with the highest refractive index.
SPARQL (Wikidata): select ?ent where { ?ent wdt:P31 wd:Q902638 . ?ent wdt:P1109 ?obj } ORDER BY DESC(?obj)LIMIT 5 
Answer: calcium carbonate, acetophenone, benzoic acid, acetone