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Which of the following statements regarding Noble gases is correct? All noble gases have a complete octet with 8  valence electrons. It is in the 18th group of the modern periodic table. All noble gases have positive electron gain enthalpy.

Which of the following statements regarding Noble gases is correct? All noble gases have a complete octet with 8  valence electrons. It is in the 18th group of the modern periodic table. All noble gases have positive electron gain enthalpy. Correct Answer Statement (ii) and (iii) is correct.

The correct answer is Statement (ii) and (iii) is correct.

  • Group 18 of the modern periodic table consists of inert gases.
    • Hence statement (ii) is correct.
  • The valence shell of the inert gases is completely filled.
  • But 'He' Helium has the atomic number 2 so it does not have an octet.
    • Hence statement (i) is incorrect.
  • Group 18 exhibits very large positive values of electron gain enthalpy.
    • Hence statement (iii) is correct.

​Notes:

  • The general configuration of the inert gas is given as ns2np6 (except helium which has 1s2).
  •  Atomic radii of noble gases increase down the group with an increase in atomic number due to the addition of new shells.
  • The elements of group 18 exhibit very high ionization enthalpies.
  • Ionization enthalpy of inert gases decreases down the group due to the increase in their atomic size.

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