Ions and Covalent Molecules

How many electrons will $$Se^{-2}$$   have? 

Select the correct name for $$P_2O_5$$  

Select the correct name for $$CO$$  

Select the correct formula for Phosphorus Trichloride

Select the correct formula for: Dinitrogen monoxide

Which element will gain 2 electrons while forming ionic compound? (Select all that apply)