Select all of the answers that apply. Which of the following characteristics must an air mass have?
It flows as one unit.
It has different temperatures but uniform humidity.
It must be 1,000 miles or more in size.
It must form over a low-pressure area.
It has a uniform temperature and humidity.

The characteristics of two different types of reactions are shown below: reaction a: electrons are gained by the atoms of an element. reaction b: protons are lost by the atom of an element. which statement is true about the atoms of the elements that participate in the two reactions? their identity changes in both reaction a and reaction b. their identity changes in reaction a but not in reaction b. their identity changes in reaction b but not in reaction a. their identity remains the same in both reaction a and reaction b.