Chemistry Class 11 NCERT Solutions: Chapter 2 Structure of Atom Part 17

Q: 54. If the photon of the wavelength Equation pm strikes an atom and one of its inner bound electrons is ejected out with a velocity of Equation calculate the energy with which it is bound to the nucleus.

Answer:

Energy of incident photon (E) is given by,

Equation

Equation

Equation

Equation

Energy of the electron ejected (K.E)

Equation

Equation

Equation

Equation

Hence, the energy with which the electron is bound to the nucleus can be obtained as:

Equation

Equation

Equation

Equation

Equation

Q: 55. Emission transitions in the paschen series end at orbit Equation and start from orbit n and can be represented as Equation

Calculate the value of n if the transition is observed at 1285 nm. Find the region of the spectrum.

Answer:

Wavelength of transition = 1285 nm

Equation (Given)

Equation (Given)

Since Equation

Equation

Equation

Equation

Equation

Equation

Equation

Hence, for the transition to be observed at 1285 nm, n=5.

The spectrum lies in the infrared region.

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