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 |
 60%
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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 |
 58%
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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 |
 68%
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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 |
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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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A 25-watt bulb emits monochromatic yellow light with a wave length of 0.57µm. The rate of emission of quanta per second would be :

1. 7.17×10-19 s-1

2. 4.13×1016s-1

3 . 7.17×1019 s-1

4 . 1.26 ×1020s-1

Subtopic:  Planck's Theory |
 66%
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The wavelength of light emitted when the electron in a H atom undergoes the transition from an energy level with n = 4 to an energy level with n = 2, is :

1. 586 mm

2. 486 nm

3. 523 nm

4. 416 pm

Subtopic:  Hydrogen Spectra |
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The energy associated with the fifth orbit of a hydrogen atom is :

1. -2.18 × 10-18 J
2. -8.72 × 10-20 J
3. -3.88 × 10-21 J
4. -8.72 × 10-19 J

Subtopic:  Hydrogen Spectra |
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The wave number for the longest wavelength transition in the Balmer series of atomic hydrogen would be :

1. \(1 .   1 . 52   \times   \left(10\right)^{6}   m^{- 1}\)
2. \(2 .   3 . 14   \times   \left(10\right)^{6}   \left(cm\right)^{- 1}\)
3. \(3 .   15 . 2   \times   \left(10\right)^{6}   m^{- 1}\)
4. \(4 .   1 . 52   \times   \left(10\right)^{6}   \left(cm\right)^{- 1}\)



 

Subtopic:  Hydrogen Spectra |
 61%
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The energy of an electron in an H - atom is given by \(E_n=(-2.18 \times10^{-18})/n^2~\mathrm J.\) The shortest wavelength of light that can be used to remove an electron completely from \(n = 2\) orbit will be:

1. \(3647~\mathring{\mathrm A}\) 2. \(5132~\mathring{\mathrm A}\)
3. \(3017~\mathring{\mathrm A}\) 4. None of these

Subtopic:  Hydrogen Spectra |
 62%
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