Final answer:
The absolute atomic mass of a tin atom can be determined by subtracting its atomic number from its relative atomic mass. In this case, the absolute atomic mass of the tin atom is 118.69 units.
Step-by-step explanation:
The absolute atomic mass of an atom is the sum of the masses of its protons, neutrons, and electrons. In the case of a tin atom with a relative atomic mass of 118.69, we can assume that it has 50 protons since the atomic number of tin is 50. To find the absolute atomic mass, we need to determine the number of neutrons in the tin atom. We can subtract the atomic number (50) from the relative atomic mass (118.69) to find the number of neutrons. Therefore, the absolute atomic mass of the tin atom is 118.69 units.