Final answer:
The atomic mass of an atom with 5 protons, 6 neutrons, and 5 electrons is 11 amu.
Step-by-step explanation:
An atom with 5 protons, 6 neutrons, and 5 electrons has an atomic mass of 11 amu. Atomic mass is calculated by adding the number of protons and neutrons in an atom's nucleus since the mass of electrons is negligible. The atomic mass unit (amu) is defined as one-twelfth of the mass of a carbon-12 atom, which has 6 protons and 6 neutrons.
Using the formula A = N + Z, where A is the mass number, N is the number of neutrons, and Z is the atomic number (the number of protons), we find that for our atom, A = 6 (neutrons) + 5 (protons) = 11 amu. Therefore, the atomic mass of the atom is 11 amu.