Darwin studied actual birds on the Galapagos Islands instead of using a simulation, List at least three possible
challenges Darwin might have faced.

The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass

Lipid because of the high percentage of carbon to carbon bonds, which store more energy than other bonds.

Im not sure if you still need this but the answer is 300 hz450 hz  i just did this lesson so , wish you the best of luck and take care