Is boiling water until salt remainds a chemical or physical?

What is the density of the black hole

0.2348 grams of pbcl2 used to form 44.0 ml of solution.

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?