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Arock can be broken down into different kinds of substances by physical processes. no chemical reactions are needed to separate different parts of a rock into pure substances. this is because a rock is a(n)

Calculate the number of molecules present in 0.750 mol of mgo.

Joe shines white light into a bowl half full of water at an angle of incident of 27.5°. calculate the angle of refraction in the water given the indices of refraction for air and water are 1.00 and 1.36, respectively.