Answer:
A. 0.603
Explanation:
Mass fraction of an element in a substance = mass of that element / total mass of the substance.
Mass of magnesium = 24.3g/mol
Mass of oxygen = 16g/mol
Total mass of MgO = 24.3+16 = 40.3g/mol
Hence, the mass fraction of magnesium in Magnesium oxide =
24.3/40.3
= 0.6029
= 0.603
Another way is to divide the percentage by mass of magnesium by 100 i.e. 60.3% = 60.3/100
= 0.603
