what are the three assumption when adding of oxide percentage to 128 in the calculation of elements because most elements bound to oxygen in the form of silicate. The elements are silicon, aluminum, iron calcium magnesium sodium, potassium and titanium have different weight of elements in crust and different weight of oxide in the crust
1. The assumption that the oxide percentages of the elements in the crust are accurate and representative of the actual composition of the Earth's crust.
2. The assumption that the elements in the crust are predominantly bound to oxygen in the form of silicates.
3. The assumption that the weight of each element in the crust, as well as the weight of the oxide of each element in the crust, remains relatively stable and consistent across different geological locations and time periods.