Final answer:
The compound that contains the MOST atoms is Al2(SO4)3, which has a total of 170 atoms.
Step-by-step explanation:
The compound that contains the MOST atoms out of the options provided is 3. Al2(SO4)3. This compound contains two aluminum (Al) atoms and three sulfate (SO4) ions.
Aluminum (Al) has an atomic number of 13, which means that it has 13 protons in its nucleus. Sulfate (SO4) ions consist of one sulfur (S) atom and four oxygen (O) atoms. Sulfur has an atomic number of 16, and oxygen has an atomic number of 8.
Therefore, Al2(SO4)3 contains a total of 2 x 13 + 3 x (16 + 4 x 8) = 2 x 13 + 3 x (16 + 32) = 2 x 13 + 3 x 48 = 26 + 144 = 170 atoms.