JEE MainChemistryClassification of Elements and Periodicity in Properties
Consider the following statements regarding the elements of Group 13: (A) The atomic radius of Ga is smaller than that of Al . (B) The first ionization enthalpy of Tl is greater than that of Ga . (C) Electronegativity continuously decreases down the group from B to Tl . (D) The increase in effective nuclear charge from Al to Ga is significantly higher than that from B to Al due to the poor shielding of 3d electrons.
Options
- A(A), (B), (C) and (D)
- B(A), (B) and (D) only
- C(A) and (D) only
- D(B), (C) and (D) only
Correct answer
B. (A), (B) and (D) only
Step-by-step solution
Statement (A) is correct. The atomic radius of Ga (135 pm) is less than that of Al (143 pm) due to the poor shielding effect of the ten 3d electrons in Ga . Statement (B) is correct. The first ionization enthalpy of Tl (589 kJ/mol) is greater than that of Ga (579 kJ/mol). This is due to the poor shielding effect of both 4f and 5d electrons in Tl , which significantly increases the effective nuclear charge on its valence electrons. Statement (C) is incorrect. The electronegativity of Group 13 elements first decrease