## Group-A

1) Derive the equation for determination of radius of nth orbit of the electron in He^{+} ion from Bohr theory. Derive the equation for energy of the electron in the nth orbit of the ion also.

2) Mention two successes of Bohr’s theory.

3) In an hydrogen atom, calculate the frequency of the ray emitted when the electron jumps from 3rd state to ground state.

4) What is Zeeman effect ? Explain it with quantum number.

5) What is black body ? Describe it with Planck’s law.

6) Explain the photoelectric effect with Einstein’s law and derive its mathematical expression.

7) Write down the Shrödinger equation for hydrogen atom in polar co-ordinates specifying the terms.

8) What is Madelung constant ? Write down Born-Lande equation specifying all terms.

9) Write down molecular orbital picture of O_{2} molecule. Explain why O_{2} is paramagnetic.

10) Give Valence Shell Electron Pair Repulsion theory and with the help of it draw the structure of SF_{4} molecule.

11) What are the essential conditions for nuclear fission to be observed ? Why is it called self-sustained process ?

12) Mass of He atom is 4·00260 amu. Determine its nuclear binding energy. [ Mass of neutron = 1·008665 amu, mass of proton = 1·007825 amu]

## Group – B

1) After radioactive decay ^{234} _{90}Th is converted to ^{200}_{82}Pb . Calculate the number of particles and β-particles decayed.

2) To which of the following ions, Bohr’s theory is applicable ? Li^{+}, Be^{3+}, H_{2}^{+} Explain.

3) Ryderg constant for isotopes of an atom differs in value. Explain why.

4) Dipole moment of NF_{3} is less than that of NH3. Give reason.

5) CH_{4}, NH_{3}, H_{2}O, and H_{2}S — arrange these compounds according to their increasing bond angles. Explain.

6) Polarisability of Helium atom is 0·4 ×10^{-24} ml. Calculate probable radius of He atom.

7) At 293K total molar polarisation of H_{2}O is 74·2 ml. Refractive index is 1·33, density 0·99 gm/ml. Calculate dipole moment of H_{2}O.

## Group – C

1) The power of a slow neutron reactor is 60000 kilowatt hour. 20% of the energy is converted to electric energy. Calculate the total amount of uranium produced if for every fission 200 MeV energy is produced.

In natural uranium 0·7% uranium is fissionable. Calculate the amount of uranium spent.

2) Explain with reason the activity of Ultraviolet spectrum and Raman spectrum of N_{2}O and NO_{2} molecule.

3) Calculate the wave number of the spectrum of 700 nm wavelength. What change does this spectrum do ? What is rotational energy of a molecule ?

4) Explain thermal stability of lead tetrahalides. Describe also the related law.

5) Give the structure of the following compounds. State the hybridisation also of the molecules. ClF_{3}, I_{3}, PF_{6}.

6) What is electronic excitation ? Explain with examples.

7) Draw the molecular orbital picture of HCl molecule.

8) Molar polaristion of cis-dichloroethylene (M.wt. 97) at 302˚K is 93·13 ml and at 403˚K is 74·35 ml. Calculate the dipole moment of the compound.