The Earth has a gravitational pull on a single nitrogen molecule (N2) in the air. In comparison, the gravitational pull of the nitrogen molecule on the Earth is: 1.) Weaker, but, no zero.
2.) Zero.
3.) The same size.
4.) Stronger.

i am single too don't feel bad

dopamine..

"it was found that some people who were taking the drug l-dopa to raise their levels of dopamine were developing schizophrenic-like symptoms supporting research a strength of the dopamine hypothesis is that there are many studies which have shown support for the neurochemical explanation."

it is very well related to a lot of things but with my limited knowledge i can confidently say that the answer is space.

the components of a vector are the parts of the vectors that are to each other.

b perpendicular