Answer:
This is because, within a period or family of elements, all electrons are added to the same shell.
The Answer should be A Light particle
Your question isn't quite clear, but if you're wondering if a chemical is polar or non-polar, you simply draw a VSEPR sketch and draw arrows where the bonds are. Only draw arrows between atoms, NOT between an atom and a lone pair of electrons. The arrow should point to the most electronegative atom (you should be given an electronegativity scale). Afterwards, you add up the arrows as vectors, and look at the sum of the vectors. If the sum is zero (CH4 is a good example), the chemical is non-polar. If the sum is a vector, the chemical is polar (H2O, or water, is polar).
i just learnt this recently but i need to look through my notes again.
The correct one is Respiratory Distress !!
As rest are not concerned with air pollution !!
