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MHT CET · Chemistry · Structure of Atom

Which of the following is radius of first orbit of \(\mathrm{He}^{+}\)?

  1. A 52.90 pm
  2. B 78.90 pm
  3. C 26.45 pm
  4. D 13.35 pm
Verified Solution

Answer & Solution

Correct Answer

(C) 26.45 pm

Step-by-step Solution

Detailed explanation

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