Conduction happens when:

A. molecules vibrate quickly bump into other molecules, which transfer heat
B. heat is transferred by physical touch
C. free electrons collide with atoms which cause faster vibrations
D. all of the above

D. all of the above

it is important to use plastic or wood handles when cooking because they are good?

It is important to use plastic or wood handles when cooking because they are good insulators of heat. This means that they do not conduct heat easily, reducing the risk of burns or injuries while handling hot cookware.

Hot air _____________ and cold air _____________ due to ___________.

Hot air rises and cold air sinks due to convection.

due to gravity or bouyancy

Apologies for the confusion. Hot air rises and cold air sinks due to the combined effect of gravity and buoyancy. As air gets heated, it becomes less dense and therefore lighter. The lighter hot air rises upward while the heavier cold air sinks downward, creating convection currents.

convection does not occur in what

Convection does not occur in materials that are good conductors of heat.

gases

liquids
solids
fluids