The p-Block Elements — Chemistry STD 11 Science — Question
Gujarat BoardEnglish MediumSTD 11 ScienceChemistryThe p-Block Elements1 Mark
MCQ
Among $\ce{III-A}$ group elements, the elements with highest and lowest $I.P$. values are:
A
$B, Tl$
✓
$B, In$
C
$B, Al$
D
$B, Ga$
✓
Answer
Correct option: B.
$B, In$
$I.P$. does not smoothly decrease down in $\text{III−A}$ group. The decrease from $B$ to $Al$ is associated with increase in size. The observed discontinuity in the $I.P.$ values between $Al$ and $Ga$, and between In and $Tl$ are due to the inability of $d-$ and $f-$electrons, which have low screening effect to compensate the increase in nuclear charge.
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