Question

If a piece of ice floating on the surface of water in a beaker melts completely, the level of water:
A) Rises
B) Remains the same
C) Falls
D) Initially rises and then falls

Answer 1

Hint: The density of ice is less than that of water. So, ice floats on water. If the ice is floating on the surface of water the volume of ice submerged in the water will be equal to the volume of water displaced by the ice cube.

Complete step by step answer:
If a piece or cube of ice is placed in a container containing water, some of its portion will remain out of the water level. As we know the fact that, the volume of ice is greater than that of the water so after melting the volume of the piece will decrease and the water level will remain the same.
So, here the water level will remain the same when the ice cube will melt. Also, Stated by Archimedes that a floating object displaces an amount of water equal to its own weight. So as the water expands when it freezes, one ounce of frozen water has a larger volume than one ounce of liquid water.
Here, the apparent weight of the ice is equal to the weight of displaced water. When the ice will melt, it will occupy the volume of displaced water. So, water remains at the same level, as it was on before. It can also be said that the density of water is more than that of ice or vice versa, so the volume of water or the water level remains the same.

Hence, the correct option is B that remains the same.

Note: Since the total volume of the ice-water system is constant, the water level will remain the same. However, if the entire ice cube was outside the water surface, then the volume of water will be added to the initial water volume. So, the water level will increase in such a case.