The atomic number of oxide depends on the element it is formed from. An oxide is a compound that contains one or more oxygen atoms combined with one or more other elements. The atomic number of an element is the number of protons in the nucleus of its atoms.
For example, the oxide of carbon, which is carbon dioxide (CO2), has an atomic number of 8. This is because it contains two oxygen atoms with atomic number 8, and one carbon atom with atomic number 6.
Similarly, the oxide of iron, which is iron oxide (Fe2O3), has an atomic number of 26. This is because it contains two iron atoms with atomic number 26 and three oxygen atoms with atomic number 8.
In general, the atomic number of an oxide can be calculated by adding up the atomic numbers of the elements it contains. This can be useful in determining the properties and behavior of the oxide in chemical reactions and other processes.