Answer:
0.0199moles
Step-by-step explanation:
The number of miles of a substance can be calculated using the formula:
Number of moles (n) = Mass (M) / Molar mass (MM)
In this question, the mass of Magnesium element (Mg) = 0.478 g while the atomic mass is 24
Therefore, number of moles of Magnesium is:
Moles = 0.478/24
Moles = 0.01992
Hence, 0.0199 moles of Magnesium are contained in 0.478 g of the element.