Q10 / 150 · MHT CET 2024 (15 May Shift 2) · Chemistry

Calculate the radius of first orbit of $\mathrm{He}^{+}$.

  • Correct answer
    A
    26.45 pm
  • B
    13.23 pm
  • C
    48.62 pm
  • D
    39.46 pm

Solution

$\mathrm{r}_{\mathrm{n}}=\frac{52.9(\mathrm{n})^2}{\mathrm{Z}} \mathrm{pm}$ $\mathrm{He}^{+}$is a hydrogen-like species having $\mathrm{Z}=2$. Radius of the first orbit of $\mathrm{He}^{+}$ $=\mathrm{r}_1=\frac{52.9 \times(1)^2}{2} \mathrm{pm}=26.45 \mathrm{pm}$

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

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