Is heated water is more or less dense than melted snow and rainwater?
Well melted snow is simply liquid water....
We know that ICE floats on water...and how do we remember this? Well think TITANIC (tho we note that a berg should be more BUOYANT in salt water. Why so?)
And so WATER is MORE DENSE than ice under standard conditions...and does not freshly fallen snow briefly float on water before it melts? (It has been a long time since I have seen snow!)
As water is heated it becomes slightly LESS dense....before it turns to steam...which of course as a gas is EVEN LESS dense. Do you follow me?