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Structure of Atom question

2020 · 8 Jan · Shift 2 · Q16
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Structure of Atom question

2020 · 8 Jan · Shift 2 · Q16

JEE MainChemistryStructure of AtomMCQ+4 / −1
The radius of the second Bohr orbit, in terms of the Bohr radius, a0, in Li2+Li^{2+}Li2+ is :
  1. A
    2a09{{2{a_0}} \over 9}92a0​​
  2. B
    2a03{{2{a_0}} \over 3}32a0​​
  3. C
    4a09{{4{a_0}} \over 9}94a0​​
  4. D
    4a03{{4{a_0}} \over 3}34a0​​
View written solutionFree

Correct answer: D

  1. For a hydrogen-like species, the radius of the nnnth Bohr orbit is given by

rn=n2a0Zr_n = \frac{n^2 a_0}{Z}rn​=Zn2a0​​

where:

  • nnn = orbit number
  • a0a_0a0​ = Bohr radius
  • ZZZ = atomic number
  1. For Li2+Li^{2+}Li2+:
  • Lithium has atomic number Z=3Z=3Z=3
  • Second Bohr orbit means n=2n=2n=2

So,

r2=(2)2a03=4a03r_2 = \frac{(2)^2 a_0}{3} = \frac{4a_0}{3}r2​=3(2)2a0​​=34a0​​

  1. Therefore, the radius of the second Bohr orbit is

4a03\boxed{\frac{4a_0}{3}}34a0​​​

  1. Comparing with the options:
  • A: 2a09\frac{2a_0}{9}92a0​​
  • B: 2a03\frac{2a_0}{3}32a0​​
  • C: 4a09\frac{4a_0}{9}94a0​​
  • D: 4a03\frac{4a_0}{3}34a0​​

Hence, the correct option is D.

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