MCQ
The correct order of the first ionization enthalpy is
  • A
    $\mathrm{Al}>\mathrm{Ga}>\mathrm{Tl}$
  • B
    $\mathrm{Ga}>\mathrm{Al}>\mathrm{B}$
  • C
    $\mathrm{B}>\mathrm{Al}>\mathrm{Ga}$
  • $\mathrm{Tl}>\mathrm{Ga}>\mathrm{Al}$

Answer

Correct option: D.
$\mathrm{Tl}>\mathrm{Ga}>\mathrm{Al}$
d
($i$) due to lanthanide contraction $\mathrm{T} \ell$ has more $I.E$. as compared to $\mathrm{Ga}$ and $\mathrm{A} \ell$

($ii$) due to scandide contraction Ga has more $I.E$. as compared to $\mathrm{A} \ell$

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