Before scientists come up with a scientific question, what do they have to do first?
a. check what other scientists have said
b. devise a hypothesis
c. do an experiment
d. make an observation

Scientist would check what other scientists have said before they come up with their own scientific question. That way they can record the results from the others and compare them with their own findings when they conduct their own experiments and record the findings.

it's says that equal and opposite force are equal

that means earth and the small piece of junk orbitingexert equal forces so gravitational attraction happens