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?

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

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

For Aluminium (Al) (atomic number: 13, mass number: 27), which one among the following statements is NOT correct?

For an element with atomic number 35, which one of the following will be the correct number of electrons in its valence shell based on Bohr’s model of an atom?

Which one among the following elements is polyatomic ?