Q16 / 160 · AP EAMCET 2023 (15 May Shift 1) · Chemistry

Match the following \begin{array}{llll} & List I & & List II \\ & (Group 13 element) & & (metallic radius, pm) \\ A & \mathrm{Al} & I & 135 \\ \mathrm{~B} & \mathrm{Ga} & II & 143 \\ \mathrm{C} & In & III & 170 \\ \mathrm{D} & \mathrm{Tl} & IV & 167 \end{array} The correct answer is

  • A
    A-I, B-II, C-IV, D-III
  • Correct answer
    B
    A-II, B-I, C-IV, D-III
  • C
    A-III, B-IV, C-II, D-I
  • D
    A-II, B-I, C-III, D-IV

Solution

The atomic radii or metallic radii of elements increases down the group due to increasing shells with the exception of Gallium $(\mathrm{Ga})$ in the $13^{\text {th }}$ group. This is due to the presence of d-subshell that offers poorer shielding of the outermost p-electrons. Thus, the order of metallic radius will be:- $$ \mathrm{Ga} < \mathrm{Al} < \mathrm{In} < \mathrm{Tl} $$

Hence, the correct answer is option: 'B'.

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