Can someone me with all 3 of these questions?

5. C.
The formula for gravitational force between two objects take into account the masses of the objects as well as the distance between them. The roughness of their surface has no effect on the gravitational pull.
6. A.
When forces are balanced, what it means is there is no net force. All the forces that are acting on the object are cancelling each other out. Something like how (-5) + 5 = 0. Hence, the answer is 0N.
7. B.
Frictional force requires an object to be in contact with another surface. If our shoes are not touching the ground, there will not be any frictional force between our shoes and the ground. So, the only answer is frictional force.