An object with density 0.5 g/cm³ is placed in a liquid with density 0.9 g/cm³. The object will:

• A. Sink
• B. Remain suspended
• C. Float
• D. Dissolve

Answer: (C)

Buoyancy works by Archimedes’ principle: the buoyant force equals the weight of the fluid displaced, so an object’s fate depends on how its density compares to the liquid’s. If the object is less dense than the liquid, the fluid can support its weight and the object will float, not sink.

Here the object’s density is 0.5 g/cm³ while the liquid’s density is 0.9 g/cm³, so the object is lighter per volume than the liquid. It will rise until the weight is balanced by the buoyant force. In a float, the submerged portion displaces enough liquid to weigh as much as the object. The fraction submerged is roughly the object's density divided by the liquid's density: 0.5/0.9 ≈ 0.556. So about 55.6% of the object will be underwater, with the rest above the surface.

It won’t dissolve just from being placed in the liquid, so dissolution isn’t implied by these densities.