How do the water molecules closest to the burner compare to the water molecules closest to the surface of the liquid? (picture of water boiling on a stovetop burner in clear container)

they are more spread out and moving faster than those at the surface.
they are closer together and moving faster than those at the surface.
they are more spread out and moving slower than those at the surface.
they are closer together and moving slower than those at the surface.

A because heat is being transferred to the water at the bottom more than the surface water. so the water is more spread out and moving faster due to temperature 

Answer;

They are more spread out and moving faster than those at the surface.

Explanation;The water molecules closest to the burner are more spread out and moving faster than those at the surface.This is because of heat transfer to the water at the bottom more than the surface water. Thus, the water is more spread out and moving faster due to temperature.The molecules at the bottom when heated they gain more kinetic energy thus they move faster, and due to the convection current they move up towards the surface of the liquid while those at the surface moves downwards moves to the bottom to occupy the space left by the molecules that were originally at the bottom.

Since the pully is a simple machine so the mechanical advantage is a 1

Answer (d) the universe had cooled enough for atoms to combine, protons and neutrons were too far apart to form nuclei;