The PH of a solution is a number that describes the concentration of hydrogen ions in the solution.
For example, if the concentration of hydrogen ions in a solution is 10-4 , the solution
has PH of 4.

Evaporation: this is when warmth from the sun causes water from oceans, lakes, streams, ice and soils to rise into the air and turn into water vapour (gas). water vapour droplets join together to make clouds! condensation: this is when water vapour in the air cools down and turns back into liquid water.

It would be (at) + cu (s)