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KCET · Chemistry · Some Basic Concepts of Chemistry

For the properties mentioned, the correct trend for the different species is in

  1. A inert pair effect \( -A l>G a>I n \)
  2. B first ionization enthalpy \( -B>A l>T l \)
  3. C strength as Lewis acid - \( \mathrm{BCl}_{3}>\mathrm{AlCl}_{3}>\mathrm{GaCl}_{3} \)
  4. D oxidizing property \( -A l^{3+}>I n^{3+}>T l^{3+} \)
Verified Solution

Answer & Solution

Correct Answer

(C) strength as Lewis acid - \( \mathrm{BCl}_{3}>\mathrm{AlCl}_{3}>\mathrm{GaCl}_{3} \)

Step-by-step Solution

Detailed explanation

Lewis acid strength decreases down the group therefore, order is \(\mathrm{BCl}_{3}>\mathrm{Al} \mathrm{Cl}_{3}>\mathrm{GaCl}_{3}\) First ionization energy for
Group 13 elements decreases down the group till Al then increases for Ga due to d-electron contraction, decrease for In
then again increases for TI due to lanthanoid contraction, that is, B \(>\mathrm{Tl}>\mathrm{Ga}>\mathrm{Al}>\mathrm{In}\).
Inert pair effect shown by heavier elements only, therefore, for \(\mathrm{Tl}\), \(+1\) oxidation states in more stable and it strong
oxidizing agent in \(+3\) states.