Question

What is the melting point of water?
(A) 6 $^{0}C$
(B) 0 $^{0}C$
(C) 9 $^{0}C$
(D) 10 $^{0}C$

Answer 1

Hint: Melting point is the temperature at the given solid to melt. The melting point for water will be the temperature at which water changes its state from solid to liquid.
Complete step by step solution:
The temperature at which water changes its state from solid to liquid is 0$^{0}C$.
Case 1-When a body exchanges heat and the temperature of the body either changes or remains constant. If the temperature of the body changes then the state of the body should remain the same.
Case 2-And when a body exchanges heat and the temperature remains the same then its state changes.
Like any other matter, water also behaves in the same way. When the state of water changes from ice to water or from water to ice its temperature remains fixed.
Hence the melting point and the freezing point of water is the same i.e. 0$^{0}C$.
It is difficult to heat any solid above its melting point because the heat which enters the solid after its melting point is used to convert the solid into the liquid state. It is, however, possible to cool some liquid below its freezing point without forming a solid. When this is done the liquid is known as a supercooled liquid.

The correct answer is option (B).

Note: The temperature can be converted into Kelvin scale, by adding 273 to it. Zero degree Celsius is equal to 273 Kelvin. The change of the state from the solid to liquid occurs due to the presence of the hyperactive atoms.