melting point because the melting point is the heat required to make an object melt anything less than this poitn will not make the substence melt.
Hypothesis is a smart guess that you make on the result of your experiment. You make this even before doing the experiment through inferential analysis. If the hypothesis you made was that, cotton will grow larger balls, then in the experiment, you should measure the cotton boll's size. The size should be in terms of diameter. So, the answer is b.
Wind, air that moves to the ground
That is called condensation