A piece of ice is placed gently on the surface of water-filled glass tumbler, and the water rises to the brim. What will happen to the level of water when the ice melts? Will the water overflow? Give reason for the answer.
Here we need too know densities of water and ice.
At 0C density of ice `= 0.9167g/(cm^3)`
At 0C density of water `= 0.9998g/(cm^3)`
Density = mass/volume
Volume = mass/density
Let us say we have 1g of solid ice.
Volume of solid ice at 0C` = 1/0.9167 = 1.0909cm^3`
Volume of water at 0C `= 1/0.9998 = 1.0002cm^3`
Now it is clear that when ice become water there is a reduction in volume. When ice melts the water level will come down. So we can say the water will not overflow.
This is only considering 0C water. At other temperatures also water behavior is same as this. Water always have a lower volume than ice.