Whether an object floats or sinks in a liquid depends upon how dense (or heavy) the objects as compared to that liquid.When an object is immersed in a liquid , any of the following three situations can be observed:
Object Sinks: If the density of an object is more than that of the liquid, the object will sink.
Examples: Iron, aluminium and stone, which are denser than water, sink in water.
Object floats: If the density of an object is less than that of the liquid, the object will float.
Examples: A piece of wood, A boat, petrol vegetable oil and icewhich are less dense than water float on it.
Object remain suspended in the liquid: If the density of the both, the liquid and the object are equal, the object will remain suspended anywhere in the liquid .
Example: If a drop of olive oil put in a mixture containing equal volumes of water and alcohol, it will neither sink nor floats but remain suspended in the mixture