Question

X2o3 express you answer as a whole number

Answer 1

 2.40 - 1.68 =0.72 g of oxigen 
moles = 0.72/16 g/mol=0.045 

moles x = 1.68/ 55.9=0.03 

0.03/0.03 = 1 = x 
0.045 / 0.03 = 1.5 = O 

to get whole numbers multiply by 2 

x2O3 

X2O3 +3 CO = 2 X + 3 CO2