Acrate filled with delicious junk food rests on a horizontal floor. only gravity and the support force of the floor act on it, as shown by the vectors for weight w and normal force n.
a. the net force on the crate is zero or greather than zero. why?
b. evidence for this is

The words "... as shown ..." tell us that there's a picture that goes along
with this question, and you decided not to share it.  That's sad and
disappointing, but I think the question can be answered without seeing
the picture.

The net force on the crate is zero.  Evidence for this is that fact that
the crate is just sitting there.  If the net force on an object is not zero,
then the object is accelerating ... it's either speeding up, slowing down,
or its the direction of its motion is changing.  If none of these things is
happening, then the net force on the object must be zero.