The number of oxygen atoms that are in 4 Al₂O₃ are 12 atoms
Explanation
- The subscript in a chemical formula indicate the number of atoms of element immediately before the subscript.
- coefficient is the number in front of the formula and tells us how many molecules of a given formula are present.
- Since 4Al₂O₃ has coefficient of 4 and the subscript of O is 3 the number of O atoms = 4 x 3=12 atoms