Question: What is the nuclear isomer with the highest neutron number whose instance of is isotope of lead?
Paraphrase: What is the nuclear isomer with the best neutron range whose occasion of is isotope of lead?
SPARQL (Wikidata): select ?ent where { ?ent wdt:P31 wd:Q846110 . ?ent wdt:P1148 ?obj . ?ent wdt:P31 wd:Q1372384 } ORDER BY DESC(?obj)LIMIT 5 
Answer: lead-212m, lead-210m, lead-208m, lead-207m, lead-206m1