This might be a tough one.
:o

Hope you enjoy the quiz
;)

The Correct Answer is . . .

2. C. 8 pounds
Air weights about 0.08 pounds per cubic foot. Scuba tanks contain as much as 104 cubic feet of air. The difference in buoyancy between a full and empty tank of this size is about 8 pounds (104 ft3 x 0.08lb/ft3= 8.32 lbs). The change in buoyancy is less for smaller cylinders, but the idea that your buoyancy increases as you use air from your tank applies no matter what size tank you use.