What is the density of water at 20 degrees Celsius?
What is the density of water at 37 degrees Celsius?
Water at -20 degrees Celsius; heat will expand matter, so at +40 degrees Celsius, water would have less density. * * * * * That would be true if there were no phase change. Unfortunately for the above answer, water freezes at 0 deg C and that phase change is accompanied by an expansion. As a result, water at 40 deg C is denser that water (ice) at -20 deg C.
20 degrees Celsius is a temperature or a temperature range on the Celsius scale, where 0 is the freezing point of water and 100 is the boiling point of water. If the air temperature is 20 degrees Celsius, the weather is cool but not cold. If a pot of water is raised in temperature by 20 degrees Celsius it is heated by a set amount. 20 degrees Celsius is the same as 68 degrees Fahrenheit.