Q9 / 75 · JEE Main 2026 (02 April Shift 2) · Chemistry

Given below are two statements:
Statement I: The second ionization enthalpy of B, Al and Ga is in the order of $B > Al > Ga$.
Statement II: The correct order in terms of first ionization enthalpy is $Si < Ge < Pb < Sn$.
In the light of the above statements, choose the correct answer from the options given below:

  • A
    Both Statement I and Statement II are true
  • Correct answer
    B
    Both Statement I and Statement II are false
  • C
    Statement I is true but Statement II is false
  • D
    Statement I is false but Statement II is true

Solution

Statement I: The second ionization enthalpy of Ga is higher than that of Al. This is due to the poor shielding effect of the ten $3d$ electrons in Ga, which increases the effective nuclear charge and holds the valence electrons more tightly. The correct order of second ionization enthalpy is $B > Ga > Al$. Thus, Statement I is false.

Statement II: The first ionization enthalpy generally decreases down the group. However, Pb has a slightly higher ionization enthalpy than Sn due to the poor shielding of $4f$ and $5d$ electrons (lanthanoid contraction). The correct order of first ionization enthalpy for Group 14 elements is $Sn < Pb < Ge < Si < C$. Thus, Statement II is false.

Both Statement I and Statement II are false.

Answer: Both Statement I and Statement II are false

Hence, the correct answer is option: 'B'.

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