Individual atoms of each element all have an equal number of protons and neutrons. only the number of electrons may vary. t or f

Proton and Neutron numbers within an atom cannot change, however, the electron number may change and form an ion. The answer is True

in chemistry, a solution’s concentration is how much of a dissolvable substance, known as a solute, is mixed with another substance, called the solvent. the standard formula is c = m/v, where c is the concentration, m is the mass of the solute dissolved, and v is the total volume

it's c. elements are placed in rows based on how may valencies electrons have.