CBSE Class 11-science Chemistry Planck's Quantum Theory

• calculate the number of emitted per by a bulb 60 watt the wavelength of bulb 2000A
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• Why ionisation energy is always positive
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• The wavelength of a spectral line for an electronic transition is inversely proportional to : (1) number of electrons undergoing transition (2) the nuclear charge of the atom (3) the velocity of an electron undergoing transition (4) the difference in the energy involved in the transition
• a photon of 3000 Angstrom is absorbed by a gas and then re-elected as two photons. One photon is red 7600  Angstrom  .  What wavelength of other photon?  Here I am knowing solution but I am not able to understand that why we are using formula ( h*c/lambda of total =  h*c/lambda of 1 +h*c / lambda of 2 ) Please solve it 
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• Solved numerical s on Plank quantum theory?  
• Light of wavelength 1281.8nm is emitted when an electron of hydrogen atom drops from 5th to 3rd energy level calculate the wavelength of the photon emitted when electron falls from 3rd to ground level. 
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