a. when water(H2O) freezes, a complicated process occurs whereas hydrogen atoms in the water molecule join side by side, to form long chains that have many branches. that is why you have snow crystals that acutally look like crystals... the long chains form like this. and also when ice is formed and it breaks, it breaks up along these chains. water freezes because all its stores eneergy is transfered to the environment arount it, forcing it to become less mobile( it doesnt have the kinetic energy to move about as thought it was a liquid) so it anchors to other water molecules...and the complicated process i also talked about happens.
b. these two metals do not combine chemically like how hydrogen and oxygen combine to form water, but, when the two metals are metled and allowed to mix and cool, then become an alloy(a mixture of two or more metals). the two metals stick together because the cohesive forces between the two are strong, like two magnets pulling each other. some alloys are stronger than one metal itself this way. the cohesive force is the delocalised electrons within the alloy that are attracted to the two metal....holding the together.
c. the sun may heat up the road previously or it may heat up the water. when this happens, the water molecule gain more kinetic energy than they alredy have and they become more active and mobile. an increase in this energy causes an increase in velocity. hence, they the moelcules start to bounce off each other till they become further apart...then the water is said to become less dense...and it rises up to the atomsphere as it becomes less dense and bombards more frequently with other molocules