Why does acid precipitation weather rocks faster then normal precipitation

In a hydrogen molecule there are a total of four charges, 2 protons in the two nuclei, and 2 electrons. how many unique charge-pairs are there (without double counting)?

A200-n force is applied to the foot-operated air pump. the return spring s exerts a 2.6-n·m moment on member oba for this position. determine the corresponding compression force c in the cylinder bd. if the diameter of the piston in the cylinder is 40 mm, estimate the air pressure generated for these conditions. state any assumptions. enter a positive number for the compression force c.

If a star is moving toward earth, it is