Q29 / 160 · TS EAMCET 2023 (12 May Shift 1) · Chemistry

The number f-electrons in +3 oxidation state of gadolinium $(Z=64)$ is $x$ and in +2 oxidation state of Ytterbium $(\mathrm{Z}=70)$ is $\mathrm{y}$. The sum of $\mathrm{x}$ and $\mathrm{y}$ is

  • A
    $13$
  • B
    $20$
  • C
    $18$
  • Correct answer
    D
    $21$

Solution

The outer electronic configuration for $\mathrm{Gd}$ and $\mathrm{Yb}$ are:- $\begin{aligned} & \mathrm{Gd}=4 f^7 5 \mathrm{~d}^1 6 \mathrm{~s}^2 \\ & \mathrm{Yb}=4 f^{14} 6 \mathrm{~s}^2 \end{aligned}$ Thus, $\mathrm{Gd}^{3+}=4 f^7$ and $\mathrm{yb}^{2+}=4 f^{14}$ Thus, $x=7$ and $y=14$ $\Rightarrow x+y=7+14=21$

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

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