The ionisation energy of hydrogen atom is 13.6 eV, the ionisation energy of helium atom would be [1988]

1. 13.6 eV

2. 27.2 eV 

3. 6.8 eV

4. 54.4 eV

Subtopic:  Bohr's Model of Atom |
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The photon radiated from hydrogen corresponding to the second line of Lyman series is absorbed by a hydrogen-like atom X in the second excited state.   As a result the hydrogen-like atom X makes a transition to nth orbit. Then:

1. X = He+, n=4 

2. X = Li++, n = 6

3. X = He+, n=9 

4. X = Li++, n = 9

 

Subtopic:  Spectral Series |
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If an electron in an hydrogen atom jumps from an orbit ni=3 to an orbit with level nf=2, the frequency of the emitted radiation is 

1. v=36 C5 R 

2. v = CR6

3. v = 5 RC36

4. v  = 6 CR

Subtopic:  Bohr's Model of Atom |
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The wavenumber of a photon in the Brackett series of a hydrogen atom is 9400R. What is the quantum number of the electron that has transited from the orbit?

1. 5

2. 6

3. 4

4. 7

Subtopic:  Spectral Series |
 63%
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In an experiment to determine the e/m value for an electron using Thomson's method the electrostatic deflection plates were 0.01 m apart and had a potential difference of 200 volts applied. Then the electric field strength between the plates is 

1. 1×104 V/m 

2. 2×104 V/m

3. 4×104 V/m 

4. 5×105 V/m

Subtopic:  Various Atomic Models |
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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 λ23 and  λ4 respectively, then approximately which one of the following is correct?

1. \(4 \lambda_1=2 \lambda_2=2 \lambda_3=\lambda_4\)
2. \( \lambda_1=2 \lambda_2=2 \lambda_3=\lambda_4\)
3. \( \lambda_1=\lambda_2=4 \lambda_3=9\lambda_4\)
4. \( \lambda_1=2\lambda_2=3 \lambda_3=\lambda_4\)

Subtopic:  Bohr's Model of Atom |
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To explain his theory, Bohr used

1. conservation of linear momentum

2. conservation of angular momentum

3. conservation of quantum  frequency

4. conservation of energy

Subtopic:  Bohr's Model of Atom |
 86%
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Bragg's law for X-rays is:

1. dsinθ = 2nλ 

2. 2dsinθ = nλ

3. nsinθ = 2λd

4. None of these

Subtopic:  X-Ray (OLD NCERT) |
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The minimum wavelength of X-rays produced by electrons accelerated by a potential difference of V volt is equal to 

1. eVhc 

2. ehcV 

3. hceV 

4. cVeh

Subtopic:  X-Ray (OLD NCERT) |
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The graph between the square root of the frequency of a specific line of the characteristic spectrum of X-rays and the atomic number of the target will be:

1.

2. 

3. 

4. 

Subtopic:  X-Ray (OLD NCERT) |
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