GENERAL KNOWLEDGE

Detailed explanation-1: -The mass number of an atom is equal to the number of protons plus the number of neutrons that it contains. In other words, the number of neutrons in any atom is its mass number minus its atomic number. Although all atoms of a given element must have the same atomic number, they need not all have the same mass number.

Detailed explanation-2: -The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus. The number of neutrons is equal to the difference between the mass number of the atom (M) and the atomic number (Z).

Detailed explanation-3: -The total number of protons plus neutrons is called the atomic mass number for the atom. Atoms are electrically neutral because the number of negatively-charged electrons is exactly equal to the number of positively-charged protons.

Detailed explanation-4: -The mass of an atom is the sum of number of protons and number of neutrons present in that atom in atomic mass unit . The total number of protons and neutrons present in a nucleus is termed as nucleon. Therefore, the mass of an atom is equal to the number of nucleons in atomic mass unit .

Detailed explanation-5: -The mass number of an atom is the sum of the number of protons and number of neutrons in an atom.