Exams › JEE Main › Chemistry

If the series limit frequency of the Lyman series is vL, then the series limit frequency of the Pfund series is:

1. 25 vL
2. 16 vL
3. vL/16
4. vL/25

Correct answer: vL/25

Solution

The series limit frequency of the Pfund series is derived from the energy levels of the hydrogen atom, specifically the transitions to the n=5 level. Since the Lyman series corresponds to transitions to n=1 and has a series limit frequency of vL, the Pfund series, which transitions to n=5, results in a frequency that is a fraction of vL, specifically vL/25.

Related JEE Main Chemistry questions

• At what wavenumber does the first line of the hydrogen Balmer series occur in the atomic spectrum?
• In the hydrogen emission spectrum, a spectral series has its limit at 12186.3 cm⁻¹. This series is identified as
• Two rapidly moving particles X and Y have de Broglie wavelengths of 1 nm and 4 nm, respectively. If the mass of X is nine times the mass of Y, what is the ratio of their kinetic energies, X: Y?
• Given that Planck’s constant is 6.63 × 10⁻³⁴ J s and the speed of light is 3.0 × 10⁸ m s⁻¹, which of the following is nearest to the wavelength, in nanometres, of light having frequency 8 × 10¹⁵ s⁻¹?
• A lithium ion and a proton are each accelerated through the same potential difference. If their de Broglie wavelengths are λ₁ and λ₂, respectively, and m_(Li) = 9mₚ, what is the ratio λ₁: λ₂?
• The ionisation energy of He⁺ is 19.6 × 10⁻¹⁸ J atom⁻¹. What is the energy of the first stationary state (n = 1) of Li²⁺?

⚔️ Practice JEE Main Chemistry free + battle 1v1 →