Question: What is the group of chemical substances with the lowest ultimate tensile strength whose topic's main category is Category:Nylon ?
Paraphrase: What kind of the chemical substances of nylon have the lowest ultimate tensile strength?
SPARQL (Wikidata): select ?ent where { ?ent wdt:P31 wd:Q17339814 . ?ent wdt:P5479 ?obj . ?ent wdt:P910 wd:Q55272807} ORDER BY ASC(?obj)LIMIT 5 
Answer: nylon