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ATOMS QUESTIONS
What is Thomson model of atom?
What is the failure of Thomson model?
What was Rutherford’s scattering experiment? Discuss briefly.
Describe alpha particle scattering experiment performed by Rutherford, Geiger and
Marsden. Write its significance.
Define distance of closed approach
Define impact parameter. What are the different factors on which depends?
Discuss the postulates of Rutherford’s model of atom.
What are the limitations of Rutherford’s model of atom?
Discuss Bohr quantization condition of angular momentum.
Find the total energy of an electron in an orbit of an atom.
What is an atomic spectrum? What do you mean by spectral series?
Discuss spectral series of H atom? What are the Bohr’s postulates?
What is Bohr’s quantization condition for the angular momentum of an electron in the
second orbit?
Find the radius of stationary orbit and energy of an electron in H atom.
The ground state energy of H atom is – 13.6eV. find the K.E and P.E of the electron
in the ground state.
Define excitation energy, ionization energy, excitation potential ,ionization potential.
Write the drawback’s of Bohr atomic orbital. Define Bohr’s radius?
a) Prove that the speed of election in the ground sate of hydrogen atom is equal to
the speed of electron in the first excited state of hydrogen like Li++ atom.
b) The total energy of and electron in the first excited state of hydrogen atom is 34.eV. Calculate (1) K.E. of the electron in this state. (2) P.E. of the electron in
this state and (3) which of the answer would change of the choice .Justify your
answer?
c) Calculate the kinetic energy and potential energy of an electron in the first orbit
of hydrogen atom. Given e = 1.6 x 10-19C and r = 0.53 x 10-10m.
d) The wavelength of the first member of Balmer series in the hydrogen spectrum
is 6563A. Calculate the wavelength of the first member of lyman series in the
same spectrum.
e) The wavelengths of some of the spectral lines obtained in hydrogen spectrum
are 9546A, 6463A and 1216A. Which one of these wavelengths belongs to
Lyman series?
f) Write the empirical relation for paschen series lines of hydrogen atom?
DUAL NATURE OF RADIATION
19 Define work function? What are the different factors on which it
depends
20 What are the different methods of electron emission?
21 What is photoelectric effect? Why Alkali metals like lithium, sodium,
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potassium, cesium etc. shows photoelectric effect with visible light
where as the metal like zinc, cadmium are sensitive to ultraviolet
light.
Discuss the experimental set up of photoelectric effect.
What is the effect of intensity of light on photocurrent?
What is the effect of potential on photoelectric current?
Define stopping or cut off potential. What is the effect of frequency of
incident radiation on stopping potential?
Discuss the variation of stopping potential with frequency of light.
What are the laws of photoelectric emission?
Derive Einstein’s photoelectric equation. Explains the laws of
photoelectric equation from Einstein equation.
How to determine Planck constant and work function from stopping
potential.
How wave theory is fail to explain photo electric effect?
What is photon and write its properties?
32 Monochromatic light of frequency 6.0 ×1014 Hz is produced by a laser.
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The power emitted is 2.0 ×10–3 W. (a) What is the energy of a photon
in the light beam? (b) How many photons per second, on an average,
are emitted by the source.
What do you mean by dual nature of radiation and matter?
Find the expression for debroglie wavelength.
Find the expression for de broglie wavelength of an electron
a) What is the de Broglie wavelength associated with (a) an electron
moving with a speed of 5.4×106 m/s, and (b) a ball of mass 150 g
travelling at 30.0 m/s?
b) An electron, an α-particle, and a proton have the same kinetic
energy. Which of these particles has the shortest de Broglie
wavelength?
c) The ratio of the de Broglie wavelength of the particle to that of
the electron is 1.813 ×10–4. Calculate the particle’s mass and
identify the particle.
d) What is the de Broglie wavelength associated with an electron,
accelerated through a potential difference of 100 volts?
Name the experiment which prove the existence of matter wave.
NUCLEI & RADIOACTIVITY
Find the expression for the radius of the nucleus.
Show that nucleus density is independent of the mass number of its nucleus.
What is nuclear force? Write the different properties of nuclear forces.
Define mass defect. Draw the variation of potential energy of a pair of nucleons with
distance between them. Write its significance.
Define binding energy per nucleon. What is the significance of B.E per nucleon?
Draw the graph showing the variation of B.E per nucleon with mass number and on
the basis of this graph explain nuclear fusion and nuclear fission
Define packing fraction. Define radioactivity. Why Nucleus disintegrate?
State radioactive decay law and find the expression for the number of undecayed
nuclei after time‘t’.
Define radioactive decay constant or disintegration constant.
Define half-life of radioactive substance.
Find the relation between number of radioactive nuclei and number of half-lives.
Define mean or average life. Write the relation between half life and mean life.
Define activity of radioactive substance. Write its S.I unit. Define units of activity.
Define nuclear fission and nuclear fusion.
What is alpha decay, beta decay and gamma decay?
Write the properties of alpha, beta particles and gamma radiations.
What is nuclear reaction? Define Q value of reaction. What is nuclear fission?
Find the energy released in nuclear fission.
What is nuclear fusion? What is stellar energy or source of energy in the sun?