Is aerated water a mixture or a compound?

Answer 1

Water would be the compound, as it is formed of one oxygen atom bonded to two hydrogen atoms. When you aerate the water, you dissolve atmospheric air (which itself is a mixture of nitrogen, oxygen, carbon dioxide, water vapor and other minor gases) into the water to create a mixture of water and air.

Answer 2

Aerated water is a mixture because the gases are actually dissolved into the water. Aerated water contains oxygen, carbon dioxide, nitrogen, and other gases.