Pure magnesium metal is often found as ribbons and can easily burn in the presence of oxygen. when 2.59 g of magnesium ribbon burns with 7.52 g of oxygen, a bright, white light and a white, powdery product are formed. enter the balanced chemical equation for this reaction. be sure to include all physical states.

Burning Mg in the air and reacting with O2 forming a white powder of MnO

So the equation is going to be:
Mn + O2 ⇒ MnO (this equation is not conserved)

to make it equilibrium:
1- First we should put 2Mno to equal the O2 on both sides.
So it will be:
Mg + O2⇒ 2MgO
2- Second we should put 2Mn to equal the Mn on both sides.
2Mg + O2⇒ 2MgO (this equation is conserved)
After putting the physical states the final equilibrium equation is going to be:
                        Δ
2Mg(s) + O2(g)⇒ 2MgO(s)

 

The correct answer is weight.