How is wavelength measured (Select all that apply. from the trough (bottom) of one wave to the trough of the next wave from the trough (bottom) of one wave to the crest (top) of the next wave
from the crest (top) of one wave to the crest (top) of the next wave
from the crest (top) of one wave to the trough (bottom) of the next wave

Wavelength is measured from crest to crest. Amplitude is from trough to crest or crest to trough

d: the voltage of the secondary coil is less than that of the primary coil.

im not suree sorry if wrong

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.