How does convection affect the crust above it?

The convection transfers the heat to the cold surface or crust in this case the crust gets warmed up from the heat. The same way if you put a pot of water or whatever on the stove the heat source is warming up the cold liquid by transfering its energy. hope this help.

Rising magma pushes againstAnd along the tectonic platesWhich eventually move the plates together

Ch4 is nonpolar and insoluble in water. since all of the hydrogen atoms are evenly spread around the carbon atom even through the c h bond is polar all the poles cancel each other out.