Answer -C They are defined by the number of electrons.
An orbital is a function that describes the probability of finding the electron with certain energy at certain distance from the nucleus therefore, it is defined by the number of electrons.
A. Chemistry
The scientific study of matter and the changes it undergoes is called chemistry
Weight is the force of gravity on an object. Weight depends on the strength of the gravitational field the object is in and the mass of the object. ... Mass is constant anywhere in the universe, whereas weight depends on the gravity where the object is present (Earth, the moon, Jupiter, etc.).