Why do clouds look white?

Answer: Water droplets scatter all light

Water droplets scatter all light ✓ — Correct! Cloud droplets are big enough to scatter all colors of light equally (Mie scattering). When all colors mix, you see white. The sky is blue because tiny air molecules scatter blue light more (Rayleigh scattering). Storm clouds look dark because they're so thick that little light gets through. At sunset, clouds turn red/orange because blue light was already scattered away earlier in the sun's path!

Clouds contain white chemicals — Wrong. Clouds are water droplets/ice crystals, not chemicals. Water scatters all wavelengths of light equally, creating white appearance.

Oxygen makes clouds appear white — Wrong. Oxygen is colorless. Cloud whiteness from large water droplets scattering all colors of light equally (Mie scattering).