Question: What carbon isotope starts with the letter "c"?
Paraphrase: What carbon isotope begins with the letter "c"?
SPARQL (Wikidata): SELECT DISTINCT ?sbj ?sbj_label WHERE { ?sbj wdt:P31 wd:Q471790 . ?sbj rdfs:label ?sbj_label . FILTER(STRSTARTS(lcase(?sbj_label), 'c')) . FILTER (lang(?sbj_label) = 'en') } LIMIT 25 
Answer: carbon-14, carbon-14, carbon-11, carbon-11, carbon-12, carbon-12, carbon-9, carbon-9, carbon-13, carbon-13, carbon-10, carbon-10, carbon-15, carbon-15, carbon-8, carbon-8, carbon-17, carbon-17, carbon-20, carbon-20, carbon-22, carbon-22, carbon-18, carbon-18, carbon-19, carbon-19, carbon-21, carbon-21, carbon-23, carbon-23