Q. Which of the following are correctly matched?

1. Mass number- denoted by M
2. Atomic number -denoted by z
3. Isotopes- same atomic number
4. Isobar- same atomic mass

Select the correct answer from the codes given below:
Answer: Only 1, 3, and 4
Notes: Atomic number is the number of protons of an atom, which determines its atomic number. It is denoted by 'Z'. the atomic number is defined as the total number of protons present in the nucleus of an atom. the mass of an atom resides in its nucleus. The mass number is defined as the sum of the total number of protons and neutrons present in the nucleus of an atom. It is denoted by 'A'. Isotopes are defined as the atoms of the same element, having the same atomic number but different mass numbers. Atoms of different elements with different atomic numbers, which have the same mass number, are known as isobars.