The weight could be different, metals have a higher mass than nonmetals, so when occupying the same amount of space, the weight of the metal is far more.
The gravitational potential energy
gpe = mgh
I feel like the answer would be B. The chair pushes down on the floor becuase the question says when you sit in a chair, your body exerts a downward force on the chair so it would be pushing downward meaning that the chair would also go down making it push onto the floor.
