I would guess that the answer to this poorly worded question is the gas because I am not aware of a gas that is denser than a liquid.
Having said that, what materials are the cylinders made of? They may be the same size, but they could be made of materials of vastly different densities - so much so that the difference is the cylinders' masses offsets the difference in the masses of the contents.
Furthermore, heavier implies the force of gravity. If you had two identical cylinders, one filled with gas and on the surface of a neutron star, and the other filled with liquid and "floating" in space, the first would be heavier - very many times heavier.
Oxygen cylinders are typically larger and heavier than acetylene cylinders due to the higher pressure at which oxygen is stored. Oxygen cylinders may also contain more volume of gas compared to acetylene cylinders.
Gold is heavier than a diamond if they are both the same size.
Yes, they have almost exactly the same dimensions, but the 4S is a bit heavier.
It depends on the size of the cylinders. Not all 4 cylinder engines are the same size.
Pressure due to a liquid increases with depth because of the weight of the liquid above it. The pressure in a liquid is the same at a given depth regardless of the shape or size of the container, as long as the depth is the same. The shape and size of the container would only affect the pressure at different depths in the liquid.
Assuming the parachutes are the same size, then yes.
Lead is more dense than ice.
No, iron is denser and heavier than polystyrene. An iron ball would weigh more than a polystyrene ball of the same size.
The interior of a ping-pong ball is filled with air, while the interior of a golf ball is made of solid material (rubbers) that are heavier (denser) than air. Thus wile about the same size a golf ball is much heavier than a ping-pong ball.
Because its density.
Because its density.
Because its density.