Substituting carbonated soft drinks for dairy products in the diet is a bad idea because the resulting high intake combined with inadequate intake leads to bone loss.

answer:

i don't believe the ocean is purple, but it might once have been:

as for the sky, according to nasa:

"sunlight reaches earth's atmosphere and is scattered in all directions by all the gases and particles in the air. blue light is scattered more than the other colors because it travels as shorter, smaller waves. this is why we see a blue sky most of the time."