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# Nuclear Decay

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1. Which radioactive emanations have a charge of -1?

A) neutrons

B) gamma rays

C) alpha particles

D) beta particles
E) none of the above

2. Complete the nuclear equation by 86Rn220 à 2He4 + ______ writing the symbol of the missing particle:

A) 84Po216

B) 84Po214

C) 82Pb218

D) 82Pb222

E) none of the above

3. Argon-37 decays via electron capture emission, which equation represents the balanced nuclear equation?

A) 18Ar37 à -1e0 + 17Cl37

B) 18Ar37 + -1e0 à 17Cl37

C) 18Ar37 + 1e0 à 17Cl37

D) 18Ar37 + -1e0 à 16S37

E) none of the above

4. Which sample will decay least over a period of 30 days?

A) 10 g of Au-198

B) 10 g of I-131

C) 10 g of P-32

D) 10 g of Rn-222

E) cannot be determined

5. An object taken from a cave has a carbon-14 fraction which is 0.89 of the amount in a living organism. How old is the object? (half-life for C-14 is 5730 yr)

A) 240 yrs

B) 480 yrs

C) 960 yrs

D) 1920 years

E) 3840 years

6. An electron emitted from the nucleus during some kinds of radioactive decay is known as:

A) A positron

B) A beta (b) particle

C) A gamma ray

D) An alpha (a) particle

E) nuclear fusion

7. Complete the equation 82Pb211 à -1e0 + ­­­­­_______ by writing the symbol of the missing particle:

A) 81Tl211

B) 83Bi211
C) 82Pb210

D) 82Pb211 +

E) none of the above

8. Complete the nuclear equation 73Ta177 electron capture à by writing the symbol of the missing particle:

A) 74W177

B) 74W178

C) 72Hf177

D) 72Hf178

E) none of the above

9. Plutonium-242 decays via alpha emission, which equation represents this balanced nuclear equation?

A) 94Pu242 à 2He4 + 92U236

B) 94Pu242 à 2He4 + 92U238

C) 94Pu242 à 1n0 + 92U238

D) 94Pu242 à 2He4 + 92Pb238

E) none of the above

10. Gamma (g) rays are:

A) are very low energy, very short wavelength electromagnetic radiation

B) are very high energy, very short wavelength electromagnetic radiation

C) are very high energy, very long wavelength electromagnetic radiation

D) are very low energy, very long wavelength electromagnetic radiation

E) none of the above

11. The half-life of Rn-222 is 3.823 day. What was the original mass of a sample of this isotope if 0.0500 g remains after 7.646 day?

A) 0.398 g

B) 0.199 g

C) 0.085 g

D) 0.800 g

E) 0.042 g

12. Which reaction illustrates fusion?

A) 1H2 + 1H2 à 2He4
B) 0n1 + 13Al27 à 11Na24 + 2He4

C) 13Al27 + 2He4 à 15P30 + 0n1

D) 7N14 + 2He4 à 1H1 + 8O17

E) all of the above

13. Complete the nuclear equation 10Ne19 à 1e0 + ______ by writing the symbol of the missing particle:

A) 9F18

B) 10Ne18

C) 9F19

D) 10Ne19

E) none of the above

14. Very large nuclei tend to be unstable because of the:

A) attraction of electrons for the positively charged nucleus

B) repulsive forces between electrons

C) attraction of protons for neutrons

D) repulsive forces between protons

E) repulsive forces between neutrons

15. 131I decays with a t1/2 = 8.07 hrs. If we begin with 3.0 mg, how much remains after 6 half-lives?
A) 0.0469 mg
B) 0.0234 mg

C) 0.50 mg

D) 0.25 mg

E) 0.01875

16. In a fusion reaction, reacting nuclei must collide. Collisions between two nuclei are difficult to achieve because the nuclei are
A) both negatively charged and repel each other

B) both positively charged and repel each other/I think this one. MG
C) oppositely charged and attract each other

D) oppositely charged and repel each other

E) none of the above

17. As the temperature of a sample of a radioactive element decreases, the half-life will
A) decrease

B) increase

C) remain the same/ I think this one. MG

D) depends on the nucleus
E) none of the above

18. Compared to chemical reactions, nuclear reactions produce:

A) proportionately far less energy

B) fewer changes in the nucleus

C) proportionately far more energy
I think this one. MG

D) different states

E) none of the above

19. Which nuclide is a radioisotope used in the study of organic reaction mechanisms?

A) carbon-12

B) carbon-13

C) carbon-14 / I think its this one. MG

D) uranium-235

E) uranium-238
20. The half-life of Pa-234 is 6.75 hr. Approximately what fraction of a sample of isotope remains after 20.25 hours?
A) ¼

B) 1/8
C) 1/16

D) 1/3

E) ½

21. The process in which a very heavy nucleus splits into more-stable nuclei of lesser mass is called:

B) a chain reaction

I think this is the answer. MG

D) nuclear fusion

E) nuclear fission
22. The half-life of Th-227 is 18.2 day. How many days are required for 0.70 of a given sample to decay?

A) 4 days

B) 16 days
Maybe this but not sure. MG

C) 32 days

D) 64 days

E) 128 days

23. In nuclear reactions:

A) small amounts of mass are converted to a large amount of energy
I think its this one. MG

B) mass and energy are destroyed

C) large amount of energy are converted to small amount of mass

D) small amount of mass are converted to large amounts of mass

E) None of the above

24. Which of the following statements is true?

A) Some naturally occurring isotopes are radioactive / it think its this one. MG
B) All naturally occurring isotopes are radioactive

C) No naturally occurring isotopes are radioactive

E) none of the above

25. Silicon-26 decays via positron emission, which equation represents the balanced nuclear equation?

A) 14Si26 à -1e0 + 13Al26

B) 14Si26 à 2He4 + 13Al26

C) 14Si26 à 1e0 + 13Al28

D) 14Si26 à 1e0 + 13Al26

E) none of the above

26. Heavy water and graphite are two examples of materials that are can be used in a nuclear reactor to slow down neutrons. These materials are called

A) fuels

B) shields

C) coolants

D) moderators / I think its moderators

E) none of the above
27. For most common types of radioactive decay, the order of least penetrating to most penetrating to human tissue is:
A) beta, gamma, alpha

B) alpha, beta, gamma I think its this one

C) gamma, alpha, beta

D) gamma, beta, alpha

E) alpha, gamma, beta

28. An alpha (a) particle is essentially a ___________ nucleus.
A) carbon-12

B) uranium

C) hydrogen/ I think its hydrogen because it is 1.0082 MW?

D) plutonium

E) helium

29. To make nuclear fission more efficient, which device is used in a nuclear reactor to slow the speed of neutrons?

A) internal shield

B) external shield

C) control rod I think its this one. MG

D) moderator

E) none of the above

30. Magnesium-28 decays via beta emission, which equation represents the balanced nuclear equation?

A) 12Mg28 à -1e0 + 14Si28

B) 12Mg28 à 2He4 + 10Ne28

C) 12Mg28 à 1n0 + 13Al28

D) 12Mg28 à -1e0 + 13Al28

E) none of the above

https://brainmass.com/physics/gamma/nuclear-decay-265699

#### Solution Preview

1. Which radioactive emanations have a charge of -1?

D) beta particles

2. Complete the nuclear equation by 86Rn220 --> 2He4 + ______ writing the symbol of the missing particle:

A) 84Po216

Since the atomic number has declined by 2, we know that we are dealing with the element with an atomic number of 84 (Po). Its atomic mass would have to be 216.

3. Argon-37 decays via electron capture emission, which equation represents the balanced nuclear equation?

B) 18Ar37 + -1e0 --->-17Cl37

For these problems, remember that the atomic number (first number) tells you the number of protons, while the second number, the mass number, tells you the number of total protons and neutrons. When an electron is combined with a proton, a neutron results. Therefore, the mass number will decrease by one.

4. Which sample will decay last over a period of 30 days?

C) 10 g of P-32

First explore whether the elements are radioactive, and the lengths of their half lives. We can see that P-32's half-life is long enough that will last at least 30 days

5. An object taken from a cave has a carbon-14 fraction which is 0.89 of the amount in a living organism. How old is the object? (half-life for C-14 is 5730 yr)

C) 960 yrs

Remember the decay equation for radioactive isotopes is rate = ln No N = kt where N0 is the amount of sample present at t = 0 and N is the amount at time t and k ...

#### Solution Summary

Multiple choice problems involving particle physics

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