Composition of Nucleus – 02

Isotones are nuclides \(\text{with:}\)

A \(\text{nucleus}\) with atomic number 8 and mass number 18 contains:

Which of the following pairs represents \(\text{isobars?}\)

Select the nuclide pair which is not an \(\text{isotone}\) pair:

Element X has atomic number 20 and mass number 40. If Y is an \(\text{isobar}\) of X with 21 neutrons, what is the atomic number of Y?

An \(\text{isotone}\) of ³⁹K (Z=19) has 21 protons. What is its mass number?