In a free expansion of a perfect gas (also called Joule expansion), we know U does not change, and no work is done. However, the entropy must increase because the process is irreversible. Are these statements compatible with the first law dU = TdS - pdV?

the answer is b i think

cant without the picture! ?

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force