Q. Consider the following statements:
1.The minimum temperature at which a solid melt to become a liquid at the atmospheric pressure is called its melting point.
2.The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point.
Which of the statements given above is/are NOT correct?

[A] 1 only

[B] 2 only

[C] Both 1 and 2

[D] Neither 1 nor 2

Answer: D
Notes:

Explanation: The minimum temperature at which a solid melt to become a liquid at the atmospheric pressure is called its melting point. The melting point of ice is 273.15 K*.

  • The process of melting, that is, change of solid state into liquid state is also known as fusion. When we supply heat energy to water, particles start moving even faster.
  • At a certain temperature, a point is reached when the particles have enough energy to break free from the forces of attraction of each other.
  • At this temperature the liquid starts changing into gas. The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point.

Source: Science NCERT 9th Class