What is the mass percent of 6.8 of sucrose in 38.4 grams of water

Can someone me with questions 15 to 17 plz.

Which process does not require the presence of a physical substance in order to transfer heat? air in the atmosphere is heated by the ground. this warm air then rises, and cooler air falls. this is an example of what type of process? how is conduction different from radiation?

Calculate the percent composition by mass of each element in al(oh)3. use at least three significant figures.