The correct option is D 50%
For the given reaction,
MgCO3→MgO+CO2
As per stoichiometry, 1 mol of MgCO3 decomposes to give 1 mol of MgO and 1 mol of CO2
Initial moles of MgCO3=4284=0.5 mol
So, theoretically,
moles of MgO produced=0.5 mol
∴mass produced=0.5×molar mass of MgO=0.5×40=20 g
But the actual yield is 10 g of MgO.
So, Percentage yield=Actual yieldTheoretical yield×100
=10 g20 g×100 =50%