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NEET Chemistry QUESTION #7423
Question 1
The correct order of atomic radii among Group 13 elements is:
  • B < Ga < Al < Tl < In
  • B < Al < Ga < In < Tl
  • B < Al < In < Ga < Tl
  • B < Ga < Al < In < Tl✔️
Correct Answer Explanation
Group 13 atomic radii — note the anomaly of Ga:
  • B (Period 2): smallest
  • Al (Period 3): larger than B
  • Ga (Period 4): slightly smaller than Al due to d-block contraction (3d¹⁰ electrons offer poor shielding)
  • In (Period 5): larger than Ga
  • Tl (Period 6): largest
Correct order: B < Ga < Al < In < Tl