[steerraiser68]

What has a greater polar covalent bond? H2O or K2O??

[Astrokel]

potassium oxide is covalent?

[SN1P3R]

I'm assuming here the question is about electronegativity, if so then in your example, (this is assuming both are covalent in a hypothetical situation), then Hydrogen is more electronegative than potassium:

Electronegativity is the ability of an atom to withdraw electron density from a covalent bond, this basically means the higher the value the more the further the electrons in the bond are towards it are.

If you have two different atoms with a covalent bond (i.e. they have different electronegativity values) the one with the higher value will have a slightly negative charge because it can pull the electrons in the bond towards it better than the other.

When looking at which is the 'greater polar bond' you mean, 'which is more polarised?', meaning 'which has the biggest difference in electronegativity between the atoms in the bond?'

This question is answered easily in you case, we know that hydrogen is more electronegative than potassium, so the difference between hydrogen and oxygen will be bigger than potassium and oxygen, therefore water has the most polar bond.

So H2O is your answer.

I hope this helped.

[nj_bartel]

I'd have to pretty much completely disagree with sniper.  What you're looking for is the difference in electronegativity.   The difference between electronegativities of K-O is much larger than H-O, so the K-O bond is much more polar.  However, it's so much more polar that I wouldn't consider classifying it as polar covalent - I'd classify it as ionic (as astrokel was pointing out).