4 degrees celsius
Troposphere
salt water is densest
when rocks are thrown in it
About 4 degrees centgrade.
Liquid water is the densest form.
The densest liquid at room temperature is Mercury which is 13.5 times heavier than water.
deep zone
The Troposphere.
Yes the densest liquid will go to the bottom, just as the second densest will go to the middle and the lightest of the 3 will be on top. However many different liquids you place in a container, it will act in the same manner as water and oil, the oil will be on the bottom and the water on top.
A basic answer is that the densest ocean water is the saltiest - a ship floats higher in salt water (sea) than in fresh water (lake). Also cold water tends to sink towards the ocean floor, or may form a layer mid way.
Polar regions produce the densest waters because of the cooling and freezing there.
All matter is densest and heaviest at precisely absolute zero, which is -273.15 degrees Celsius.