Step-by-step explanation:
a)Take percentages and divide by mole wt ( from periodic table) of the corresponding element
C 14.25 / 12 = 1.1875
O 56.93 / 15.99 = 3.56
Mg 28.83/24.3 = 1.186 Divide by the smallest number
C 1.1875/1.186 = 1
O 3.56 / 1.186 = 3
Mg 1.186 / 1.186 = 1
C O3 Mg commonly written as Mg CO3 ( magnesium carbonate)