The correct answer is 11
Step-by-step explanation:
In chemistry, each atom contains protons, neutrons, and electrons. The atomic mass number of an isotope (a variant of a chemical element) can be determined by adding the number of protons and neutrons. Additionally, the number of protons is equivalent to the atomic number that is usually the same according to the element. Additionally, the number of electrons has no or little influence on the atomic mass number. This implies, if an isotope has an atomic number of 5 it has 5 protons and this added to the 6 neutrons of the isotope makes the atomic mass number of this isotope 11 or 5 protons + 6 neutrons = 11 (atomic mass number).