(When) or (What) is the due date ? Ex: for the assignment

when is the due date?

Explanation:

1. asking for information specifying something.

"wha t is your name?"

2.asking for repetition of something not heard or confirmation of something not understood.

"what? I can't hear you"

3. the thing or things that (used in specifying something).

"what we need is a commitment"

3.(referring to the whole of an amount) whatever.

"I want to do what I can to make a difference"

4. (in exclamations) emphasizing something surprising or remarkable.

"what some people do for a crust!"

when

Explanation:

because it is a date