Its temperature rises. As 40C is the temperature where water has its maximum density, then the density will drop as well
When a sample of water is heated past 100 degrees Celsius, it is past its boiling point. At this temperature, water changes from a liquid to a gas.
Evaporates
The water gets heated up and turns into a gas
It evaporates
It boils
it will now occur evaporation
Water is transformed in vapors.
Water heated to above the boiling point (steam), or below the vapor pressure for water in the gas sample with water vapor in it.
The can collapses and closes in on itself.
what happens to water molecules when they are heated
It bubbles up dummy.
Its molecules become heated.