Given below are two statements : Statement (I) : The first ionization energy of Pb is greater than that of…

Given below are two statements :
Statement (I) : The first ionization energy of Pb is greater than that of Sn.
Statement (II) : The first ionization energy of Ge is greater than that of Si.
In the light of the above statements, choose the correct answer from the options given below :
  1. Statement I is false but Statement II is true
  2. Statement I is true but Statement II is false
  3. Both Statement I and Statement II are true
  4. Both Statement I and Statement II are false

Solution

First ionization energy of Lead $=715 \mathrm{~kJ} \mathrm{~mol}^{-1}$
First ionization energy of Tin $=708 \mathrm{~kJ} \mathrm{~mol}^{-1}$
$\left(\mathrm{IE}_1\right)$ of Lead is greater than that of Tin due to ineffective shielding of d - and f -electrons.
Therefore Statement-I is true.
First ionization energy of Germanium $=761 \mathrm{~kJ} \mathrm{~mol}^{-1}$
First ionization energy of Silicon $=786 \mathrm{~kJ} \mathrm{~mol}^{-1}$
$\left(\mathrm{IE}_1\right)$ of Germanium is lower than that of Silicon as the effect of higher atomic radius of Ge outweighs the increase in nuclear charge from Si to Ge and effective shielding of inner electrons.
Therefore Statement-II is false.

Asked in: JEE Main 2025 (24 Jan Shift 2)

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