Question
The wavelength of spectral line obtained in the spectrum of Li ^ 2+ ion, when the transition takes place between two levels whose sum is 4 and difference is 2, is
JEE Main
Chemistry
Structure of Atom
2026
JEE Main 2026 (24 January Shift 2)
JEE Main Chemistry Question (2026) — Solution
Options
- A. 1.14 10^ -7 ~cm
- B. 1.14 10^ -6 ~cm
- C. 2.28 10^ -7 ~cm
- D. 2.28 10^ -6 ~cm
Answer
B. 1.14 10^ -6 ~cm
Step-by-step solution
For Li²⁺ (Z=3): From n_2 + n_1 = 4 and n_2 - n_1 = 2, we get n_2 = 3, n_1 = 1 Using Bohr wavelength formula: 1 = RZ^2 ( 1 n_1^2 - 1 n_2^2 ) 1 = 1.097 10^7 9 (1 - 1 9 ) = 9.873 10^7 8 9 1 = 8.776 10^7 m⁻¹ = 1.14 10^ -6 cm
Related: Chemistry — Structure of Atom · All PYQ Banks