Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength 6800 Å. The work function (W0) of the metal is: 

1. 3.109 × 10–20 J

2. 2.922 × 1019 J

3. 4.031 × 1019 J

4. 2.319 × 1018 J

Subtopic:  Photo Electric Effect |
 78%
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Determine the maximum number of emission lines produced when an electron in a hydrogen atom transitions from the n = 6  energy level to the ground state :

1. 30

2. 21

3. 15

4. 28

Subtopic:  Hydrogen Spectra |
 81%
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The ionization energy for H atom in the ground state is \(2.18 \times10^{-18}~ \mathrm J.\) The process energy requirements will be: \(( He^+(g) \rightarrow He^{2+}(g) + e^- )\)

1. \(8.72 \times10^{-18}~\mathrm J\) 2. \(7.54 \times10^{-18}~\mathrm J\)
3. \(5.67 \times10^{-17}~\mathrm J\) 4. \(2.18 \times10^{-17}~\mathrm J\)
Subtopic:  Hydrogen Spectra |
 60%
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The ejection of the photoelectron from the silver metal can be stopped by applying a voltage of 0.35 eV when the radiation having a wavelength of 256.7 nm is used. The work function for silver metal is: 

1. 3.40 eV

2. 5.18 eV

3. 4.48 eV

4. –4.40 eV

Subtopic:  Photo Electric Effect |
 62%
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Property which is same for the following species is:

 N3, O2–, F, Na+, Mg2+ and Al3+ 

1. Ionic radii

2. Number of electrons

3. Nuclear charge

4. None of the above 

Subtopic:  Number of Electron, Proton & Neutron |
 88%
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The total number of electrons present in one mole of methane is:

1. 6.023 × 1023
2. 6.023 × 1024
3. 6.023 × 1022
4. 1.619× 1023

Subtopic:  Number of Electron, Proton & Neutron |
 61%
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The total number and mass of neutrons in 7 mg of 14C would be :

(Assume that mass of a neutron = 1.675 × 10–27 kg)

\(1 .\) \(2 . 41\) \(\times\) \(\left(10\right)^{21}\) \(,\) \(4 . 03\) \(\times\) \(\left(10\right)^{– 6}\) \(kg\)
\(2 .\) \(6 . 23\) \(\times\) \(\left(10\right)^{23}\) \(,\) \(1 . 67\) \(\times\) \(\left(10\right)^{- 21} kg\)
\(3 .\) \(1 . 22\) \(\times\) \(\left(10\right)^{22}\) \(,\) \(4 . 03\) \(\times\) \(\left(10\right)^{6}\) \(kg\)
\(4 .  2 . 41\) \(\times\) \(\left(10\right)^{21}\) \(,\) \(4 . 03\) \(\times\) \(\left(10\right)^{- 6}\) \(g\)

Subtopic:  Number of Electron, Proton & Neutron |
 59%
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The wave number of a light whose time period is 2.0 × 10–10 s would be:

1. 16.66 m–1

2. 1.66 m–1

3. 32.34 m–1

4. 12.34 m–1

Subtopic:  Introduction of Atomic Structure |
 69%
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The number of photons of light with a wavelength of 4000 pm that provide 1J of energy would be: 

1. 2.01 × 1016
2. 2.01 × 1019
3. 4.14 × 1023
4. 2.14 × 1021

Subtopic:  Planck's Theory |
 70%
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Electromagnetic radiation of wavelength 242 nm is just sufficient to ionise sodium atom. The ionisation energy of sodium in kJ mol–1 is :

1. 494

2. 4.94

3. 516

4. 0.50

Subtopic:  Planck's Theory |
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