There are two elements - calcium (atomic number 20) and argon (atomic number 18). The mass number of both the elements is 40. They are therefore known as

Which one of the following elements will be an isobar of calcium if the atomic number of calcium is 20 and its mass number is 40?

Atomic mass of an element is equal to the sum of number of

The number of electrons and neutrons in an element is 18 and 20 respectively. Its mass number is

What is the mass number of an element, the atom of which contains two protons, two neutrons and two electrons?

The mass number of argon is 40. Which one of the following statements is correct?