It is an alkaline earth metal.
In this item, we are simply to find the ions that may bond and are able to form a formula unit. We are also instructed to give out their name. There are numerous possible combinations of ions to form a compound. Some answers are given in the list below.
1. Na⁺ , Cl⁻ , NaCl ---> sodium chloride (this is most commonly known as table salt)
2. C⁴⁺ , O²⁻ , CO₂ ---> carbon dioxide
3. Al³+ , Cl⁻ , AlCl₃ ----> aluminum chloride
4. Ca²⁺ , Cl⁻ , CaCl₂ ---> calcium chloride
5. Li⁺ , Br⁻ , LiBr ---> lithium bromide
6. Mg³⁺ , O²⁻ , Mg₂O₃ ----> magnesium oxide
7. K⁺ , I⁻ , KI ---> potassium iodide
8. H⁺ , Cl⁻ , HCl --> hydrogen chloride
9. H⁺ , Br⁻ , HBr ----> hydrogen bromide
10. Na⁺ , Br⁻ , NaBr ---> sodium bromide
To separate off different products in order of their boiling points. You do it by a process of heating and cooling in a horizontal condenser usually.
In all atoms, the number of protons and the number of electrons is always the same. The number of neutrons is very roughly the same as the number of protons, but sometimes it's rather more. The number of protons in an atom is called the atomic number and it tells you what type of atom you have.
The law of conservation of mass dictates that the total mass of reactants must be equal to the total mass of the products. Thus:
mass(MgO) = mass(Mg) + mass(O)
mass(MgO) = 24 + 16
mass(MgO) = 40 g
The third option is correct.
