How do you tell if a compound is ionic or non polar

Question

Question:

Ionic, polar covalent and non-polar compounds

How do you tell if a compound is ionic, polar covalent, or non-polar? Find out for these compounds (Big numbers are used to represent the number of atoms because they are all 1 molecule.)

a) Na₂SO₄
b)KOH
c)(NH₄)₂SO
d) C₆H₁₄
e)C₂H₅OH
f)H₂0