1. Heat flows from your hand to the cold water in the process called diffusion. Heat moves from a place where it's highly concentrated to a place of lower concentration, but the solutions want to go to equilibrium. So the heat is going to flow between the hand and the cold water until its at equilbrium. The answer is d.
2. Freezing is the opposite of melting. The answer is b.
3. Gold weighs a lot more than leaves. The molecular weight of gold is 196.97 grams/mole. The answer is c.
4. A chemical property is a property of matter that changes as a result of chemical reaction. The process of making pizza is a chemical process that requires chemical reactions. The answer is d.
5. Physical property is a property of matter that can be observed without an chemical reaction. Oil is more dense than water. This why oil floats on top of water.The answer is b.
6. Homogenous mixture is a mixture that contains one type of element or compound. Graphite is a compound contains carbon. The answer is c.