What specifically does str measure?
a) str length
b) the number of repeating units
c) distance traveled on electrophoresis gel
d) the difference between the number of repeating units between two strs

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.

Answer is to avoid experimental error