Ah , a cup of hot chocolate is alot of chocolate. Im gonna drool ; )
Well , heat flows from an area of high temperature to an area of low temperature. Here , hot chocolate has the high temp , and the surrounding has a room temp. So , the heat from the hot chocolate will dissipate into the surroundings and create a thermal equilibrium. So youre right.
36 divided by 12 is 3. you need three times as much of the recipe to make 36 brownies. The answer is B
A mixture can be separated. Everything in a mixture keeps it's own properties and are not chemically joined together. I am not completely sure about the compound. Although with the cake example, the ingredients have been mixed and kind of "fused" together upon baking. Hope this helps a little. (P.S. trail mix is a good example of a mixture.)