# The energy of an electron in an excited hydrogen atom is $$-3.4~\text{eV}$$.  Its angular momentum will be: ($$h = 6.626\times 10^{-34}$$ J-s) 1. $$1.11\times 10^{34}~\text{J-s}$$ 2. $$1.51\times 10^{-31}~\text{J-s}$$ 3. $$2.11\times 10^{-34}~\text{J-s}$$ 4. $$3.72\times 10^{-34}~\text{J-s}$$

Subtopic:  Bohr's Model of Atom |
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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. $$122.4$$

Subtopic:  Bohr's Model of Atom |
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The wavelength of Ka X-rays produced by an X-ray tube is 0.76 $\stackrel{\circ }{A}$. Find the atomic number of the anode material of the tube?

1. 41

2. 30

3. 20

4. 10

Subtopic:  X-Ray (OLD NCERT) |
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According to Bohr's theory, the moment of momentum of an electron revolving in second orbit of hydrogen atom will be:
1. $$2\pi h$$
2. $$\pi h$$
3. $$\frac{h}{\pi}$$
4. $$\frac{2h}{\pi}$$

Subtopic:  Bohr's Model of Atom |
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The ionisation energy of a hydrogen atom is $$13.6~\text{eV}$$. Following Bohr's theory, what is the energy corresponding to a transition between the $$3^{th}$$ and $$4^{th}$$ orbit?
1. $$3.40~\text{eV}$$
2. $$1.51~\text{eV}$$
3. $$0.85~\text{eV}$$
4. $$0.66~\text{eV}$$

Subtopic:  Bohr's Model of Atom |
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The ratio of the energies of the hydrogen atom in its first to second excited states is

1. $\frac{1}{4}$

2. $\frac{4}{9}$

3. $\frac{9}{4}$

4. 4

Subtopic:  Bohr's Model of Atom |
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Energy levels A, B, C of a certain atom correspond to increasing values of energy i.e. ${E}_{A}<{E}_{B}<{E}_{C}.$ If  are the wavelengths of the radiation corresponding to the transitions C to B, B to A and C to A respectively, which of the following relation is correct?

1. ${\lambda }_{3}={\lambda }_{1}+{\lambda }_{2}$

2. ${\lambda }_{3}=\frac{{\lambda }_{1}{\lambda }_{2}}{{\lambda }_{1}+{\lambda }_{2}}$

3. ${\lambda }_{1}+{\lambda }_{2}+{\lambda }_{3}=0$

4. ${\lambda }_{3}^{2}={\lambda }_{1}^{2}+{\lambda }_{2}^{2}$

Subtopic:  Spectral Series |
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In the Rutherford scattering experiment, what will be the correct angle for $\propto$-scattering for an impact parameter, b = 0?

1. ${90}^{\circ }$

2. ${270}^{\circ }$

3. ${0}^{\circ }$

4. ${180}^{\circ }$

Subtopic:  Various Atomic Models |
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The velocity of the electron in the ground state (H - atom) is

1.

2.

3.

4.

Subtopic:  Various Atomic Models |
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The element which has K$\alpha$ X-ray line whose wavelength is 0.18 nm is:

1. Cobalt

2.  Xenon

3. Copper

4. Iron

Subtopic:  Spectral Series |
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