The ionisation energy of a hydrogen atom is 13.6 eV. Following Bohr's theory, what is the energy corresponding to a transition between the 3^rd and 4^th orbit?
1. 3.40 eV
2. 1.51 eV
3. 0.85 eV 
4. 0.66 eV

The energy of 24.6 eV is required to remove one of the electrons from a neutral helium atom. What is the energy (in eV) required to remove both the electrons from a neutral helium atom?

1.  38.2

2.  49.2

3.  51.8

4.  79.0

The radius of a hydrogen atom in its ground state is 5.3×10^-11 m. After collision with an electron, it is found to have a radius of 21.2 ×10^-11 m. What is the principal quantum number n of the final state of the atom?

1. n = 4 

2. n = 2 

3. n = 16 

4. n = 3

A hydrogen atom is in an excited state of principal quantum number (n). It emits a photon of wavelength ($\lambda$) when it returns to the ground state. The value of n is:

1. $\sqrt{\frac{\lambda R}{\lambda R-1}}$ 

2. $\sqrt{\frac{(\lambda R-1)}{\lambda R}}$

3. $\sqrt{\lambda (R-1)}$ 

4. None of these

The given diagram indicates the energy levels of a certain atom. When the system moves from the 2E level to E, a photon of wavelength λ is emitted. What is the wavelength of the photon produced during its transition from the $\frac{4E}{3}$ level to E?

1. $\frac{\lambda }{3}$ 

2. $\frac{3\lambda }{4}$ 

3. $\frac{4\lambda }{3}$ 

4. $3\lambda$

The wavenumber of a photon in the Brackett series of a hydrogen atom is $\frac{9}{400}R$. What is the quantum number of the electron that has transited from the orbit?

1. 5

2. 6

3. 4

4. 7

Hydrogen ₁H¹, Deuterium ₁H², singly ionised helium (₂He⁴)⁺, and doubly ionised lithium (₃Li⁶)⁺⁺ all have one electron around the nucleus. Consider an electron transition from n = 2 to n = 1. If the wavelengths of emitted radiations are λ₁ ,λ₂ ,λ₃ and  λ₄ respectively, then approximately which one of the following is correct?

As per the Bohr model, the minimum energy (in eV) required to remove the electron from the ground state of a double ionised lithium ion (Z = 3) is:

1. 1.51

2. 13.6 

3. 40.8

4. 122.4

The energy of an electron in an excited hydrogen atom is -3.4 eV.  Its angular momentum will be:
(h = 6.626 $\times$ 10^-34 J-s)

1. 1.11 $\times$ 10³⁴ J s 

2. 1.51 $\times$10^-31 J s

3. 2.11 $\times$ 10^-34 J s

4. 3.72 $\times$ 10^-34 J s

The frequency of the series limit of the Balmer series of hydrogen atoms in terms of Rydberg constant R and velocity of light C is:

1. $\frac{RC}{4}$

2. RC

3. $\frac{4}{RC}$

4. 4RC