Which one of these compounds is an ionic compound? question 18 options: n2 na2o co2?

Types of Bonds can be predicted by calculating the difference in electronegativity.

If, Electronegativity difference is,

                Less than 0.4 then it is Non Polar Covalent

                Between 0.4 and 1.7 then it is Polar Covalent 

                Greater than 1.7 then it is Ionic

For N₂,

                    E.N of Nitrogen      =   3.04

                    E.N of Nitrogen      =   3.04

                    E.N Difference             0.00         (Non Polar Covalent)

For Na₂O,

                    E.N of Oxygen       =   3.44

                    E.N of Sodium       =   0.93

                    E.N Difference             2.51         (Ionic)

For CO₂,

                    E.N of Oxygen       =   3.44

                    E.N of Carbon       =    2.55

                    E.N Difference             0.89         (Polar Covalent)

the answer is c.the valence of the atoms combine .