Calculator permitted.  Formulas Provided  (do not write on formula sheets)

 

  1. Excited iron atoms emit green light of wavelength 527 nm.  Calculate the energy of these photons and compare the value with that of photons from BBC radio of wavelength 1500 m.

 

 

  1. What is the deBroglie wavelength of an electron, m = 9.1 x 10-31 kg, and a velocity , v = 3 x 105 m/s.?

 

  1. Remembering the order in which orbitals are filled, determine the electron configuration of Iodine (Z = 53).

 

 

 

  1. The bond energies of the diatomic molecules O2 and N2 are 4.93 x 108 J/k mol and 9.40x108 J/k mol respectively.  What is meant by bond energy, and what are the reasons for the difference in these values?  Calculate the energy, in eV, required to separate each molecule into its constituent atoms.  The Hydrogen bond between water molecules has energy 5.00 x 107 J/k mol.   Give reasons for its low value compared with those above.  What frequency of radiation is required to dissociate two water molecules?

 

 

  1. The concentration of an element in a sample may be determined by X-Ray fluorescence, where atoms are excited by X-Rays and emit characteristic X-Rays which are detected and counted.  Copper atoms emit such fluorescent X-Rays of wavelength 0.154 nm.  What is the minimum tube voltage required to excite this fluorescence?

 

  1. A sample of  128I53  contains 2.0 x 1010 radioactive nuclei. (a) If the half-life of this isotope is 25 minutes, calculate the decay constant.  (b) How many nuclei are still radioactive after 24 hours?

 

  1. A standard source containing 2.0 mCi of tritium is monitored by a liquid scintillation counter and 120 cps are recorded.  Calculate the activity of  a sample which gives a count rate of 270 cps.

 

  1. Radiocarbon dating is based on the assumption that the ratio of C-14 to stable C-12 atoms in the atmosphere has remained constant for thousands of years, and that all living organisms contain this prescribed ratio of carbon atoms.  Upon death, C-14 incorporation ceases and the amount then present decays at the characteristic rate with a half life of 5580 years.  Therefore the determination of the specific activity of carbon fixes the time of death.  The specific activity of a sample of carbon from a wood relic is 4.5 nCi/kg.  If the specific activity of a sample of old wood is 0.28125 nCi/kg today, how old is the sample of wood?
  2. In the Bohr model of the atom, an electron making transitions from a higher energy state to a lower energy state produces discrete line spectrum. When the electron makes a transition from a state with an energy of  - 0.544 ev to a state having an energy of - 3.40 ev.  What is the wavelength of the photon emitted?

 

  1. Given that the energy level for a certain element is given by En = .   What is the frequency of a photon emitted from a transition from a n=4 to an n=2 state?

 

11.       The Pauli Exclusion Principle states

            a. No two electrons can have the same set of quantum numbers.

            b) There is an inherent uncertainty in the position and momentum of a particle

            c) When an atom has orbitals of equal energy, the maximum number of electrons will have unpaired spins

            d) when an electron is in a stationary orbit it will not radiate energy

 

12.  Find the binding energy (in Mev) of carbon-12. 

Assume:   mC = 11.996706 u    mp = 1.007276 u        mn = 1.008665 u

 

 

13. Radioactive polonium,  decays by alpha emission to:

            a.           b.           c.            d.           e.

 

14. The same spectroscope is used to obtain the five spectra in the figure below:  What elements can you identify in sample (a) and in sample (b)?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


15. . Determine the energy, Q value,  for the reaction :    2713Al + 10n ® 2411Na  + 42He

 

He    4.002603            Al     26.981541             Na       23.990964            n     1.008665

 

16. . Deuterons that have been accelerated to a high velocity have been used to bombard other deuterium nuclei, resulting in the reaction:

 

21H   +   21H  ®   32He  +  10n              What is the Q value for this reaction?

 

21H  = 2.014102         32He =  3.016029         10n   =   1.008665

 

 

17. The function of the “control rods” in a nuclear reactor is to:

a)increase fission by slowing down the neutrons

b)decrease the energy of the neutrons without absorbing them

c) decrease fission by absorbing neutrons

d) increase the ability of the neutrons to cause fission

e) provide the critical mass for the fission reaction

 

18. The purpose of  a “moderator” in a nuclear reactor is to:

  1. provide neutrons for the fission process
  2.  react with the uranium to release energy
  3. slow down fast neutrons to increase the probability of fission
  4. absorb the dangerous gamma radiation
  5. shield the reactor operator from dangerous radiation

 

19. For a controlled nuclear fusion reaction, one needs:

  1. high density n and high temperature T
  2. high n and low T
  3. low n and high T
  4. low n   and low T
  5. high n and T = 0 °K

 

20. A spaceship is measured to be 120 m long while it is at rest with respect to an observer.  If this spaceship now flies past the observer with a speed of 0.99 c,  what length will the observer measure for the length of the spaceship?

 

21. Describe the difference between Nuclear fission and Nuclear Fusion.