When 24g of Magnesium reacts with oxygen gas the only product is magnesium oxide. If 40g magnesuim is produced how much oxygen was consumed?

2 answers

2Mg + O2 ==> 2MgO

You must mean if 40 g magnesium OXIDE are produced and you must be using 24 for the atomic mass Mg and 40 as molar mass MgO. In those circumstances.
mols Mg = 24/24 = 1 mol and that will produce 40 g MgO.
mols O2 consumed = 40g MgO x (1 mol O2/2 mol MgO) = 40 x 1/2 = 20 mols O2.
Then grams O2 = mols x molar mass.
THE PRODUCT OF MAGNESIUM +OXYGEN LOOK LIKE IS (soft /hard) IN A FORM OF A (LIQUID /SOLID /GAS) AND IS (WHITE /BLACK /YELLOW) IN COLOUR