What property of oil makes it float on water?
The correct answer and explanation is :
The property of oil that makes it float on water is its lower density compared to water.
Explanation:
Density refers to the mass of an object per unit volume, often expressed in grams per cubic centimeter (g/cm³). Water has a density of about 1 g/cm³ at room temperature, while most oils have a density lower than this, typically ranging from 0.8 to 0.9 g/cm³. This difference in density is the primary reason why oil floats on water.
When substances are placed in water, whether they sink or float depends on their relative densities. If an object’s density is greater than that of water, it will sink; if it is less, it will float. Since oil is less dense than water, it forms a layer on the surface rather than mixing with water.
The phenomenon can be understood in terms of the principle of buoyancy, which is described by Archimedes’ principle. This principle states that an object submerged in a fluid experiences an upward force equal to the weight of the fluid it displaces. When an object is less dense than the fluid, the upward buoyant force is greater than the object’s weight, so it floats.
Additionally, oils are generally hydrophobic, meaning they do not mix with water. Water molecules are polar, and oil molecules are non-polar, which causes the oil and water to form separate layers when they come into contact. The molecular difference further prevents the two from mixing and contributes to the formation of an oil layer on top of water.
In summary, oil floats on water primarily because of its lower density, which leads to a buoyant force that is greater than the force of gravity acting on the oil, combined with its inability to mix with water due to differences in molecular structure.