Someone plz explain how Individual bond polarities cancel out each other, thus leading to a non-polar molecule

Question

I am really struggling to understand how you can determine if a molecule is polar or not through its symmetry and vector sum. Plzzzz help me understand this.

Answer 1

The best way to predict molecule polarity is :
POLAR :
AB linear molecule
HAx molecules with a single H
AxOH molecules with an OH at one end such CH3CH2OH
OxAy molecules with O at one end as H2O
NxAy molecules with an N at one end as NH3

NON POLAR
Ax all elements ( Cl2, F2,)
CxAy most carbon compounds ( CCl4 , CO2 )
I hope this can help you

Answer 2

Draw the molecular structure on a paper and assign the vector directions.