Question

Explain the difference in polarity between co2 and h2o by referring to the polarity of the bonds and the shape of the molecules

Answer 1

Both H2O and CO2 have polar covalent bondings (O is more electronegative than H or C) . The main molecular difference arises from their different geometry. 

Answer 2

CO2 is a linear molecule so despite of having to dipolar bonds they add up and exactly cancel each other rendering the molecule non-polar.