iron oxide Reacts with aluminum to give aluminum oxide ad iron. what kind of chemcal reaction is this

What is the angular momentum of the bar about the axle?

Under the action of a constant force an object accelerates at 7.8 m/s2. what will the acceleration be if (a) the force is halved? (b) the object's mass is halved? (c) the force and the object's mass are both halved? (d) the force is halved and the object's mass is doubled?

If you put a helium-filled balloon in the refrigerator, what will happen?