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MHT CET · Chemistry · Structure of Atom

Calculate radius of third orbit of \(\mathrm{He}^{+}\).

  1. A \(52.9 \mathrm{pm}\)
  2. B \(105.8 \mathrm{pm}\)
  3. C \(238.1 \mathrm{pm}\)
  4. D \(423.2 \mathrm{pm}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(238.1 \mathrm{pm}\)

Step-by-step Solution

Detailed explanation

\(
\mathrm{r}_{\mathrm{n}}=\frac{52.9(\mathrm{n})^2}{\mathrm{Z}} \mathrm{pm}
\)
\(\mathrm{He}^{+}\)is a hydrogen-like species having \(\mathrm{Z}=2\). Radius of the third orbit of \(\mathrm{He}^{+}\)
\(=\mathrm{r}_3=\frac{52.9 \times(3)^2}{2} \mathrm{pm}=238.1 \mathrm{pm}\)