Answer: B. Na
Step-by-step explanation:
The element with 11 protons is sodium (Na), which has an atomic number of 11, indicating the number of protons in the nucleus of an atom of sodium. The atomic number uniquely identifies each element, so any element with 11 protons in its nucleus is sodium.
In addition, the atom in question has 11 electrons, which are equal in number to the protons, as atoms are electrically neutral. Furthermore, the atom has 12 neutrons, which is the total number of nucleons (protons and neutrons) in the nucleus. The atomic mass of sodium is approximately 23, which means that the most common isotope of sodium has 12 neutrons. Therefore, the atom in question has one more neutron than the most common isotope of sodium.
In summary, the atom described has 11 protons, 11 electrons, and 12 neutrons, which are the characteristics of a sodium atom with an atomic mass of approximately 23.