Question

1.0g of magnesium is burnt with 0.56g O2(oxygen) in a closed vessel . Which reactant is left in excess and how much ? (At. wt. Mg = 24 ; O = 16)

Answer 1

2Mg +O2---------> 2MgO

here we see
32 g O2 react with 48 g Mg
1 g O2 react with 3/2 g Mg
0.56g react with 0.84g Mg
hence Mg is left

excess amount of Mg=1-0.84=0.16g