Question

The number of protons in an uncharged atom __________.

A) equals the number of neutrons

B) varies with the different isotopes

C) equals the number of electrons in the outer orbital of the atom

D) determines its mass number

E) equals the number of electrons

Answer 1

The number of protons in an uncharged atom equals the number of electrons, which ensures electrical neutrality. The atomic number indicates an element's identity, and isotopes vary by neutron number, affecting mass number.

Step-by-step explanation:

The number of protons in an uncharged atom equals the number of electrons. This balance ensures the atom is electrically neutral. The number of protons in the nucleus of an atom is its atomic number (Z), which determines the identity of the element. For example, an atom with six protons is carbon, with an atomic number of 6. Isotopes of an element have the same number of protons but different numbers of neutrons, thereby differing in mass number (A), which is the sum of protons and neutrons. However, the mass of an atom largely depends on its protons and neutrons, with the electrons contributing minimally to the atom's mass. Therefore, the number of protons is critical for both the elemental identity and electrical neutrality of the atom.