Seudónimo Seudónimo 06-11-2016 Chemistry contestada Percentage composition Percentage of Mg in MgO Percentage of oxygen in CO2 Percentage of calcium in CaCO3 Percentage of Nitrogen in H2NO4 Percentage of carbon in CaCO3 Percentage of chlorine in MgCl2 Percentage of oxygen in CaCO3 Percentage of Iron Fe2O3 Percentage of oxygen in Mg(OH)2 please show all working out for each question