Ice floats in seawater because of the density relationship between ice and seawater.

• A. Ice is less dense than seawater
• B. Seawater is less dense than freshwater
• C. Ice has the same density as seawater
• D. Ice dissolves in seawater

Answer: (A)

Buoyancy is all about density: an object will float if its density is less than the surrounding liquid because the liquid can push upward with a force equal to the weight of the displaced liquid. Ice has a density around 0.92 g/cm^3, while seawater is denser, about 1.025 g/cm^3 due to dissolved salts and typical temperatures. Because the ice is less dense, the buoyant force on it exceeds its weight, so it rises and sits with part of itself above the water. The other statements don’t fit because seawater is not less dense than freshwater, ice doesn’t dissolve in seawater, and ice does not have the same density as seawater.