I'm a bit confused... If you'd say: 'Would that be possible?' What would the proper ending be? Je to možná? Je to možno? Je to možné? (It seems to me that možná and možno is used to say possibly, but the á ending makes it look more like an adjective) And would 'To jde.' be a proper response? (It'll work/be possible)
I think that in the expression "Je to možné", "možné" is an adjective in the nominative neuter because it is modifying the neuter subject "to". Another common phrase is "Možná, že...". Here "možná" is a verb conjugated in the third person singular with the implied subject "to". I'll let a real Czech native suggest the best possible responses. Another interesting one to think about is "Nic není nemožné".
I'm sorry. After my last post I started to doubt what I wrote, and sure enough according to my dictionary I was wrong. In the second example I gave, "možná" is actually an adverb, not a verb. Please forgive me for not checking first.
"Je to možné?" is correct. Pronoun "to" always refer to neuter. That means suffix "-é" is correct ("-ý" in colloquial speech). The word "možná" could be adjective (female form) or adverb (english equivalent is maybe).
