If all the light waves are absorbed by an object then the object will apear what color

When light hits a surface, some of it is absorbed and some of it is reflected. The light that is reflected is the color of the object in that light. For example, a blue object absorbs all the colors of the spectrum except blue, it reflects blue light. hope this can help.

b i think it’s a water wheel turning in a stream

if you mean hydrogen and oxygen then water is the product