Nuclear Chemistry

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1. Which of the following statements correctly distinguishes a nuclear reaction from a chemical reaction?

   1. A A nuclear reaction involves a change in the nucleus, resulting in the transmutation of one element into another, whereas a chemical reaction involves only the rearrangement of electrons.
   2. B A nuclear reaction releases less energy than a chemical reaction because it involves weaker forces.
   3. C A chemical reaction changes the number of protons in the nucleus, while a nuclear reaction only affects the electron cloud.
   4. D Nuclear reactions are always exothermic, while chemical reactions are always endothermic.

2. A radioactive isotope has a half-life of 14 days. If a sample initially contains 800 g of the isotope, how many grams will remain after 42 days?

   1. A 100 g
   2. B 200 g
   3. C 50 g
   4. D 400 g

3. Consider the nuclear equation: 238/92 U -> 234/90 Th + X. What is the particle X?

   1. A A beta particle
   2. B An alpha particle
   3. C A gamma ray
   4. D A neutron

4. A radioactive isotope of Polonium-210 (atomic number 84) decays by emitting an alpha particle to form a stable isotope of Lead. Which of the following represents the balanced nuclear equation for this decay?

   1. A 210/84 Po -> 214/86 Rn + 4/2 He
   2. B 210/84 Po -> 206/82 Pb + 4/2 He
   3. C 210/84 Po -> 210/85 At + 0/-1 e
   4. D 210/84 Po -> 206/84 Po + 4/0 n

5. A sample of a radioactive substance has an initial activity of 800 counts per minute. After 12 hours, the activity has decreased to 100 counts per minute. What is the half-life of the substance?

   1. A 2 hours
   2. B 6 hours
   3. C 8 hours
   4. D 4 hours

6. A radioactive isotope of Technetium-99 has a half-life of 6 hours. If a sample initially contains 800 mg of the isotope, how much will remain after 18 hours?

   1. A 200 mg
   2. B 100 mg
   3. C 400 mg
   4. D 50 mg

8. Complete the following nuclear equation for the alpha decay of Uranium-238: 238/92 U -> ? + 4/2 He

   1. A 234/92 U
   2. B 234/90 Th
   3. C 236/90 Th
   4. D 234/88 Ra

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