Students conduct an investigation to synthesize magnesium oxide by burning a strip of magnesium in the presence of oxygen in the air (chemical equation: 2Mg(s) + O2 (g)→ 2MgO). A bunsen burner is used to heat the crucible containing the magnesium until it burns with the air inside the crucible. The students leave the lid slightly open to keep the magnesium oxide inside but allow air to come in to completely finish the reaction. A diagram of the experimental setup is shown below.

If the students had measured the mass of the magnesium and the crucible prior to the experiment, predict how the mass will compare when the students measure the magnesium oxide and the crucible after it has cooled down.

A. The mass reading will be larger as the number of magnesium atoms present will increase when magnesium oxide is formed when it reacts with the air.

B. The mass reading will be larger as the incoming air brought in additional oxygen atoms to react with the magnesium to form magnesium oxide.

C. The mass reading will be the same as the incoming air brought in additional oxygen atoms to replace some of the magnesium to form magnesium oxide.

D. The mass reading will be the same as the magnesium oxide that formed took magnesium atoms out of the strip and oxygen atoms out of the air in the crucible.