1. Fill in the blank: 222Ra ______ + 4He
2. Supposed you have 80 grams of an isotope with a halflife of 5 days. How many grams will have you left after 20 days? – 5 grams
3. One possibility for the fission of 235U is 235U + n 144Ba + 89Kr + 3n + energy
Given the masses of the nuclei involved, determine the energy released in this process. – 173 MeV

 235U 235.0439 u
 144Ba 143.9228 u
 89Kr 88.9177 u
 n 1.0087 u
4. A city requires about 2000 million W of electric power. The complete fissioning of 1kg of 235U produces 82 trillion J of energy. If the fission energy is converted to electric energy with an efficiency of 30%, how many kg of 235U will provide the daily electric energy needs of the city? – 7.024kg
5. About 100,000,000 Btu of heat is needed annually for heating an average house in the central United States. (a) If this energy were obtained from coal having a heat content of 10,000 Btu per pound, how many pounds of coal are required? (b) The complete fissioning of one pound of 235U produces 50,000,000,000 Btu of energy. If all the fission energy could be converted to heat, how many pounds of 235U would be required to provide the 100,000,000 Btu for space heating? – 0.002 pounds 235U
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