Chemistry Class 11 NCERT Solutions: Chapter 2 Structure of Atom Part 4

Q: 9. A photon of wavelength Equation the work function of the metal being Equation Calculate

(i) The energy of the photon (eV)

Image of Energy of a Photon for Structure of Atom

Image of Energy of a Photon

Image of Energy of a Photon for Structure of Atom

(ii) The kinetic energy of the emission

(iii) The velocity of the photoelectron (1 eV= Equation ).

Answer:

(i) Energy (E) of a photon = Equation

Where,

Equation

Equation

Equation Wavelength of photon Equation

Substituting the values in the given expression of E:

Equation

Hence, the energy of the photon is Equation .

(ii) The kinetic energy of emission Equation is given by

Equation

Image of Kinetic energy for Structure of Atom

Image of Kinetic Energy

Image of Kinetic energy for Structure of Atom

Equation

Equation

Equation

Equation

Hence, the kinetic energy of emission is 0.97 eV.

(iii) The velocity of a photoelectron ( Equation ) can be calculated by the expression,

Equation

Equation

Where, ( Equation ) is the kinetic energy of emission in joules and ‘m’ is the mass of the photoelectron. Substituting the value in the given expression of v:

Equation

Equation

Equation

Hence, the velocity of the photoelectron is Equation

Q: 10. Electromagnetic radiation of wavelength 242 nm is just sufficient to ionize the sodium atom. Calculate the ionization energy of sodium in Equation Equation

Image of Electromagnetic Radiation for Structure of Atom

Image of Electromagnetic Radiation

Image of Electromagnetic Radiation for Structure of Atom

Answer:

Energy of Sodium (E) Equation

Equation

Equation

Equation

Equation

Q: 11. A Equation watt bulb emits monochromatic yellow light of wavelength of Equation Calculate the rate of emission of quanta per second.

Image of watt bulb emits monochromatic for Structure of Atom

Image of Watt Bulb Emits Monochromatic

Image of watt bulb emits monochromatic for Structure of Atom

Answer:

Power of bulb, Equation

Energy of one photon, Equation

Substituting the values in the given expression of E:

Equation

Equation

Rate of emission of quanta per second

Equation

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