Question

Ice floats on the surface of water because its density is _ _ _ _ _ that of water.
(A). less than
(B). greater than
(C). same as
(D). can’t say

Answer 1

- Hint: Density of an object determines whether it floats or sinks in a liquid. In this case, take the case of icebergs in the ocean, what does it signify?

Complete step-by-step solution -

Ice is water in its solid phase, it has the same composition of hydrogen and oxygen atoms present in water. Usually, the density of water increases as temperature decreases. But water shows an anomalous behaviour at ${{4}^{\circ }}C$, if we decrease the temperature below ${{4}^{\circ }}C$ the density keeps on decreasing instead of increasing. This is why ice at ${{0}^{\circ }}C$ is less dense than water.
What differs in ice is that the structure of water molecules in liquid form and water molecules in solid form differs. There is a regular pattern in the arrangement of water molecules in the solid phase (ice) while there is no definite pattern of molecules in the liquid phase. As the solid phase molecules attain a regular structure, the molecules spread out which in turn decreases the density of the ice.

So the answer to the question is option (A)- less than.

Note: The instrument to measure the density of a liquid is called a hydrometer. In liquid water, each molecule of hydrogen is bonded to approximately 3.4 other water molecules. In ice, each molecule of hydrogen is bonded to 4 other water molecules.