Can you tell me if these are right please?

Question

When 2.50g of copper reacts with oxygen the copper oxide product has a mass of 2.81g. What is the simplest formula of the copper oxide.
I got Cu2O (copper (I) oxide).

Aluminum and oxygen gas react to produce aluminum oxide.

A.) write a balanced equation for the relation. I got 4Al+3O2=2Al2O3

B.) If 12 moles of Al2O3 are produced how many moles of aluminum reacted? I got 24 moles.

C.) if 75g of oxygen react how many grams of aluminum are required. I got 84.4 grams.

Using the rules for writing the formulas of ionic compounds, write the ions correct formula for magnesium oxide.

I got Mg2+O2= MgO is this right?

Answer 1

I agree with all of your answers but I would write the equation for the formation of MgO differently.
2Mg + O2 ==> 2MgO
MgO consists of Mg^+2 ion and O^-2 ion.