A push or pull is your answer
I think that the answer could be A. X and Y
Answer: sp2 hybridized orbital
Explanation:
The lone pair in pyridine is contained in an sp2 hybridized orbital pointing outwards from the ring. As a result, the lone pair does not contribute to the aromatic ring but still influences the properties of pyridine such as electrophilic attack. The image attached depicts the bonding in pyridine.
If my memory serves me well, each period in the periodic table corresponds to a principal energy level. I think it's correct because periods are the horizontal rows and when you go down you always add <span> one to the principal energy level. Hope it is clear. Good luck!</span>