Which strategy should you use to determine the number of neutrons in
an atom?

For all atoms with no charge, the number of electrons is equal to the number of protons. The mass number, 40 is the sum of the protons and the neutrons. To find the number of neutrons, subtract the number of protons from the mass number. number of neutrons=40−19=21.

because the light is a great source of energy for the plants to survive. (i hope this )