The charge on the oil drop is –1.282 × 10–18C. The number of electrons present in it would be :

1. 15

2. 8

3. 2

4. 6

Subtopic:  Number of Electron, Proton & Neutron |
 81%
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An element with a mass number of 81 contains 31.7% more neutrons as compared to protons. The atomic symbol of the element would be :

1. Br3581
2. Br3681
3. Br3579
4. Br3679

Subtopic:  Number of Electron, Proton & Neutron |
 67%
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An ion with a mass number of 56 contains 3 units of positive charge and 30.4% more neutrons than electrons. The symbol of the ion is :

1. Fe+32656
2. Fe+32657
3. Fe+32758
4. Fe+32556

Subtopic:  Number of Electron, Proton & Neutron |
 67%
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A nitrogen laser produces radiation at a wavelength of 337.1 nm. If the number of photons emitted is 5.6 × 1024,
the power of the laser is:

1. 4.56 × 107 J
2. 3.33 × 106 J
3. 1.29 × 106 J
4. 9.17 × 105 J

Subtopic:  Planck's Theory |
 74%
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If the photon detector receives a total of 3.15×10-18 J from the radiation of 600 nm,
the number of photons received by the detector would be: 

1. 102
2. 10
3. 50
4. 20

Subtopic:  Planck's Theory |
 73%
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A radiation source emitted  2.5 × 1015 photons in 2 nanoseconds. Energy of the source is :

1. 8.28 × 10-10 J
2. 8.24 × 1010 J
3. 7.12 × 10-11 J
4. 2.12 × 10 10 J

Subtopic:  Planck's Theory |
 55%
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Emission transitions in the Paschen series end at orbit n = 3 and start from orbit n and can be represented as v = 3.29 × 1015 (Hz)132- 1n2The value of n if the transition is observed at 1285 nm is :

1. 6 2. 5
3. 8 4. 9

Subtopic:  Hydrogen Spectra |
 63%
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If the velocity of the electron is 1.6 × 106 ms-1. The de Broglie wavelength associated with this electron is:  

1. 590 pm
2. 455 pm
3. 512 pm
4. 401 pm

Subtopic:  De Broglie Equation |
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The characteristic velocity associated with a neutron that has a wavelength of 800 pm is :
 

1. 496 m s-1 2. 567 m s-1
3. 494 cm s-1 4. 501 m s-1
Subtopic:  De Broglie Equation |
 51%
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The velocity associated with a proton moving at a potential difference of 1000 V is 4.37 × 105 ms–1. If the hockey ball of mass 0.1 kg is moving with this velocity, then the wavelength associated with this velocity would be:

1. 1.52 ×10-38 m
2. 2.54 × 10-32 m
3. 1.52 × 10-36 m
4. 3.19 × 10-34 m

Subtopic:  De Broglie Equation |
 67%
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