JEE Main20266 April 2026Evening ShiftChemistryStructure of AtomActual
The Bohr radius of a hydrogen like species is 70.53 pm. The species and the stationary state (n) are respectively (Given : Hydrogen atom Bohr radius is 52.9 pm)
Options
- ALi ²⁺, 3
- BHe ^+, 3
- CHe ^+, 2
- DLi ²⁺, 2
Correct answer
D. Li ²⁺, 2
Step-by-step solution
The radius of the n -th Bohr orbit for a hydrogen-like species is given by the formula: r_n = a₀ n^2 Z where a₀ is the Bohr radius of the hydrogen atom ( 52.9 pm), n is the principal quantum number, and Z is the atomic number. Given r_n = 70.53 pm, we can write: 70.53 = 52.9 n^2 Z n^2 Z = 70.53 52.9 = 1.333 = 4 3 Checking the given options: For Li ²⁺ and n = 3 , Z = 3 n^2 Z = 9 3 = 3 For He ^+ and n = 3 , Z = 2 n^2 Z = 9 2 = 4.5 For He ^+ and n = 2 , Z = 2 n^2 Z = 4 2 = 2 For Li ²⁺ and n = 2 , Z = 3 n^2 Z = 4 3 The