What is the function of the noun clause in this sentence We won't know who the student chose for the cheerleader till Monday morning?

The noun clause is "whom the students chose for cheerleader", which is the direct object of the verb "know".

NOTE: The relative pronoun 'whom' is not correct. Although the noun clause is functioning as the direct object of the verb "know", the relative pronoun is the subject of the relative clause.

The sentence should read:

We won't know who the students chose for cheerleaderuntil Monday morning?