How are contact forces and non-contact forces similar?

Which statement about the stamps is correct?

An alloy contains 66 g of pure zinc. what is the percentage of zinc in the alloy? express your answer to two significant figures and include the appropriate units.

Asubstance is held in an open container. its particles move past one another at random speeds but do not leave the container. heat is removed from the system, and the particles slow down. when enough heat is removed, the particles no longer have enough speed to overcome the weak attractive forces between them. when this happens, the substance enters its solid state. the process described above is known as .