Explanation :
Atomic number is defined as the number of protons or number of electrons.
Atomic number = number of protons = number of electrons
Atomic mass is defined as the sum of number of protons and number of neutrons.
Atomic mass = Number of protons + Number of neutrons
(a) 4 protons, 4 electrons, and 5 neutrons
Atomic number = Number of protons = Number of electrons = 4
Atomic mass = Number of protons + Number of neutrons
Atomic mass = 4 + 5 = 9
The element that contains 4 protons, 4 electrons, and 5 neutrons is, Beryllium and the symbol is, (Be).
(b) 23 protons, 23 electrons, and 28 neutrons
Atomic number = Number of protons = Number of electrons = 23
Atomic mass = Number of protons + Number of neutrons
Atomic mass = 23 + 28 = 51
The element that contains 23 protons, 23 electrons, and 28 neutrons is, vanadium and the symbol is, (V).
(c) 54 protons, 54 electrons, and 70 neutrons
Atomic number = Number of protons = Number of electrons = 54
Atomic mass = Number of protons + Number of neutrons
Atomic mass = 54 + 70 = 124
The element that contains 54 protons, 54 electrons, and 70 neutrons is, xenon and the symbol is, (Xe).
(d) 31 protons, 31 electrons, and 38 neutrons
Atomic number = Number of protons = Number of electrons = 31
Atomic mass = Number of protons + Number of neutrons
Atomic mass = 31 + 38 = 69
The element that contains 31 protons, 31 electrons, and 38 neutrons is, gallium and the symbol is, (Ga).
