Answer:
Wavelength.
Explanation:
1 period, or wavelength, is measured from one crest to another or from one trough to another.
Answer:
The First State Was Delaware. Delaware was made a state in December 7, 1787. It was made a state a week before Pennsylvania.
Give Brainliest if you please
Answer:
13
Explanation:
The mass of an atom= number of protons + number of neutrons