A scientist is studying two isotopes of sodium, labeled A and B. In Isotope A, each of the atoms has 11 protons, 12 neutrons, and 11 electrons. What could be the atomic structure of Isotope B?

Isotopes are variants of a particular chemical element which differ in neutron number (neutral particle) and all isotopes of a given element have the same number of protons (positive particle) in each atom. So isotope B of the sodium will have 11 protons, 11 electrons but it may have a wide range in its number of neutrons.