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)

(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

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

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.

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

Explore Solutions for Chemistry