Asked in PMC Practice Test 20 (2021) 2021Moderate

Melting and Boiling points depend on _?

Correct answer: B. Number of Unpaired electrons

  • A. Number of electrons
  • B. Number of Unpaired electrons
  • C. Number of Paired electrons
  • D. Number of Protons

Explanation

Melting point: The constant temperature at which a solid changes into liquid is called melting point. Example : Ice cubes start melting and change state from a solid to liquid at the temperature of 0°C.Boiling point: The temperature at which the pressure exerted by the surroundings upon a liquid is equaled by the pressure exerted by the vapor of the liquid; under this condition, addition of heat results in the transformation of the liquid into its vapor without raising the temperature. If the number of unpaired electrons increases then metallic bond becomes stronger and hence the metal elements show high melting and boiling point.

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