The downward reaction force of an object is its weight.

You have a 10 lb lead ball and a 1 lb lead ball. Both dropped at the same time from 10' high. Which one hits the ground first?

They cannot fall at the same time, this is precise information.

Which one hits the ground first?

Ahahaha. It changes which high you get as 10'. If you get the center of the objects, then it means 10lb lead ball closer to the ground. Hence, it hits first. Generally we get distance of objects with their center of weight, hence, most of the events, the bigger one hits first mostly.

If you get the high as bottom of objects, then the center of weight of 1lb ball stays closer to the ground. In this point, air resistance affects should be calculated. We should calculate but I guess we can get small one hits first because of its center of weight is closer to the ground, hence it goes more than the bigger one. Ahaha. Not so easy, right?