The Bohr model of the atom:

1. Assumes that the angular momentum of electrons is quantized

2. Uses Einstein's photoelectric equation

3. Predicts continuous emission spectra for atoms

4. Predicts the same emission spectra for all types of atoms

When a hydrogen atom is raised from the ground state to excited state

1. both KE and PE increase

2. both KE and PE decrease

3. PE increases and KE decreases

4. PE decreases and KE increases

The extreme wavelengths of Paschen series are

1. 0.365 $\mu m$ and 0.565 $\mu m$

2. 0.818 $\mu m$ and 0.189 $\mu m$

3. 1.45 $\mu m$ and 4.04 $\mu m$

4. 2.27 $\mu m$ and 7.43 $\mu m$

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

Consider an electron in the \(n^\mathrm{th}\) orbit of a hydrogen atom in the Bohr model. The circumference of the orbit can be expressed in terms of the de-Broglie wavelength \(\lambda\) of that electron as:
1. \((0.529)n\lambda\)
2. \(\sqrt{n\lambda}\)
3. \((13.6)n\lambda\)
4. \(n\lambda\)

In the Bohr's model of a hydrogen atom, the centripetal force is furnished by the Coulomb attraction between the proton and the electron.  If ${\alpha }_0$ is the radius of the ground state orbit, m is the mass and e is the charge on the electron, ${\epsilon }_0$ is the vaccum permittivity, the speed of the electron is  [1998]

1. zero         

2. $\frac{e}{\sqrt{{\epsilon }_0{a}_{0}m}}$

3. $\frac{e}{\sqrt{4{\mathrm{\pi \epsilon }}_0{\mathrm{a}}_0\mathrm{m}}}$ 

4. $\frac{\sqrt{4{\mathrm{\pi \epsilon }}_0{\mathrm{a}}_0\mathrm{m}}}{e}$

The ground state energy of H-atom is 13.6 eV. The energy needed to ionise H-atom from its second excited state [1991]

1. 1.51 eV

2. 3.4 eV

3. 13.6 eV

4. 12.1 eV

          
1. \(\frac{\lambda}{3}\)
2. \(\frac{3\lambda}{4}\)
3. \(\frac{4\lambda}{3}\)
4. \(3\lambda\)

The wavelength of the first spectral line in the Balmer series of hydrogen atom is 6561 $\stackrel{0}{A}$. The wavelength of the second spectral line in the Balmer series of singly ionized helium atom is [IIT-JEE 2011]

1. 1215 $\stackrel{0}{A}$ 

2. 1640 $\stackrel{0}{A}$

3. 2430 $\stackrel{0}{A}$ 

4. 4687 $\stackrel{0}{A}$

Energy E of a hydrogen atom with principal quantum number n is given by $E=\frac{-13.6}{n^2}eV$.  The energy of a photon ejected when the electron jumps from n = 3 state to n = 2 state of hydrogen, is approximately [2004]

1. 1.5 eV 

2. 0.85 eV 

3. 3.4 eV 

4. 1.9 eV