Question

he ratio of wavelength of first line of Lyman series of
doubly ionized lithium atom to that of the first line of
Lyman series of deuterium (1H2
) will be
Example
A. 4 : 1 B. 1 : 4 C. 9 : 1 D. 1 : 9

Answer 1

• The ratio of wavelengths of first line of Lyman series in  Li⁺² and first line of Lyman series in deuterium  H² is 1/9.

We know that for the first line of Lyman series means

n₁ = 1 and

n₂ = 2

Wavelength of the lines can be given by -

1/λ = R Z² [1/n₁² - 1/n₂²] where λ is the wavelength, R is constant, Z is atomic number.

For both the atoms line transition is same, so n₁ and n₂ will be constant.

Which means-

λ ∝ 1/Z²

Z for lithium is 3 and for deuterium is 1. So by putting the values

λ Li²⁺ / λ H₂ = 1 / (3)² = 1/9