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JEE Main 202522 JanuaryMorning Shift
Exam
JEE Main
Year
2025
Date
22 January
Shift
Morning Shift
Subject
Chemistry
Chapter
Structure of Atom

JEE Main 2025 · 22 January · Morning Shift · Chemistry · Structure of Atom

Radius of the first excited state of Helium ion is given as : a_0...

Radius of the first excited state of Helium ion is given as : a0→\mathrm{a}_0 \rightarrow radius of first stationary state of hydrogen atom.

Options

  1. Ar=4a0\mathrm{r}=4 \mathrm{a}_0
  2. Br=2a0\mathrm{r}=2 \mathrm{a}_0
  3. Cr=a02r=\frac{a_0}{2}
  4. Dr=a04r=\frac{a_0}{4}

Correct answer

B. r=2a0\mathrm{r}=2 \mathrm{a}_0

Step-by-step solution

r=a0(n2z)r=a0(2)2(2)r=2a0\begin{aligned} & \mathrm{r}=\mathrm{a}_0\left(\frac{\mathrm{n}^2}{\mathrm{z}}\right) \\ & \mathrm{r}=\frac{\mathrm{a}_0(2)^2}{(2)} \\ & \mathrm{r}=2 \mathrm{a}_0\end{aligned}
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