SSC MTS EXAM

Detailed explanation-1: -Consider oxygen, which has an atomic number (Z) of 8. This means that oxygen atoms have 8 protons. Most atoms of oxygen also have 8 neutrons. Oxygen atoms with 8 neutrons would have a mass number of 16 (8 p+ + 8 n0), meaning they would have a mass of about 16 amu.

Detailed explanation-2: -Oxygen-16 (16O) is a stable isotope of oxygen, having 8 neutrons and 8 protons in its nucleus. It has a mass of 15.99491461956 u.

Detailed explanation-3: -Mass number is number of protons plus number of neutrons here, number of protons eight and number of neutrons 10, so it will be eight plus 10, And that will be 18. So the mass number of this oxygen atom is 18, and that is the last option.