How many letters does the top answer for “of or relating to a quantum or capable of existing in only one of two states” have?

The most common answer is quantal (7 letters).

Crossword clue: of or relating to a quantum or capable of existing in only one of two states

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

quantal 7 letters wn-def

of or relating to a quantum or capable of existing in only one of two states

quantized 9 letters wn-def

of or relating to a quantum or capable of existing in only one of two states