Why is xenon monatomic but bromine is diatomic

If the density of water is 1.0 g/cm3, which of these materials would float in water, based on their densities? check all that apply. aluminum cork iron lead wax

If 1.8 l of water is added to 2.5l of a 7.0 molarity koh solution, what is the molarity of the new solution

Which scenario is most similar to the type of collision that gas particles have according to kinetic molecular theory