Which molecule contains non-polar covalent bond?

Answer 1

Any molecule where the two atoms bonded together have the same electronegativity - e.g. an element such as O2. Some molecules can have polar bonds but be non-polar overall if the polarity of the bonds 'cancel out', e.g. CO2, CCl4, NH4+ This happens if the bonds are pointing in opposing directions - draw out a diagram of CO2 which has two polar double bonds to see this. Remember to consider the shape of the molecules (including lone electron pairs) when looking at the polarity of the whole molecule.