Calcium reacts with the oxygen in the air, forming calcium oxide. write the balanced chemical equation for this reaction. what is the sum of the coefficients?

Calcium react with oxygen to form calcium oxide that is quicklime or burnt lime which is white at room temperature

The balanced chemical equation is

2Ca (s) + O2 (g) - - - >2CaO (S) - a white solid at room temperature

2 moles of Ca reacted with 1 mole of O2 while to form 2 moles of CaO

hence the sum coefficient = 2+1+2=5