1) An endothermic reaction is a reaction where heat is "absorbed" and the surrounding area is cooled. An example of an endothermic reaction is the classic baking soda and vinegar reaction. The mixture gets cold.
An exothermic reaction is one which gives off heat, such as burning, which is itself a chemical reaction.
2) (I don't actually know this one but i hope i helped with number one)
To calculate the number of moles we will use Avogadro's number, which relates the number of molecules contained in a mole of any substance, the relationship between moles and molecules is as follows:

In the statement we are given the molecules with 3 significant figures, therefore the answer must also have 3 significant figures. So the answer will be: In 5.25x10^29molecules are 8.72x10^5 mol of sucrose
Physical change because the matter in the object is not chemically changing
A the solid.
it’s solid because solid is harder than gas and liquid which makes it a greater structure