Question 1

Calculate the mass defect in Ni-59 if the mass of a Ni-59 nucleus is 58.69344 amu.The mass of a proton is 1.00728 amu and the mass of a neutron is 1.008665 amu.

Accepted Answer

To calculate the mass defect, we need to first calculate the mass of the individual protons and neutrons in Ni-59.

Number of protons in Ni-59 = 28
Mass of 28 protons = 28 x 1.00728 amu = 28.19984 amu

Number of neutrons in Ni-59 = 31
Mass of 31 neutrons = 31 x 1.008665 amu = 31.258715 amu

Now, we can calculate the expected mass of the Ni-59 nucleus if all its protons and neutrons were separate particles:

Expected mass = mass of protons + mass of neutrons
Expected mass = 28.19984 amu + 31.258715 amu
Expected mass = 59.458555 amu

However, the actual mass of the Ni-59 nucleus is given as 58.69344 amu. This means that there is a mass defect:

Mass defect = expected mass - actual mass
Mass defect = 59.458555 amu - 58.69344 amu
Mass defect = 0.765115 amu

Therefore, the best choice is B) 0.779 amu, which is the closest to the calculated mass defect.

Question 2

Calculate the mass defect in Mo-96 if the mass of a Mo-96 nucleus is 95.962 amu.The mass of a proton is 1.00728 amu and the mass of a neutron is 1.008665 amu.

Accepted Answer

The mass defect is calculated by subtracting the actual mass of the nucleus from the sum of the masses of its protons and neutrons. Mo-96 has 42 protons (since Mo is the 42nd element) and 54 neutrons (96 - 42 = 54). The total mass of protons and neutrons is (42 * 1.00728 amu) + (54 * 1.008665 amu) = 42.30576 amu + 54.46811 amu = 96.77387 amu. The mass defect is 96.77387 amu - 95.962 amu = 0.81187 amu, which rounds to 0.812 amu.

Question 3

The amount of energy required to break apart the nucleus into its component nucleons is the

Accepted Answer

Nuclear binding energy is the amount of energy required to break apart the nucleus into its component nucleons. This is because the strong nuclear force holds the nucleons together in the nucleus, and breaking them apart requires energy. The other choices are not directly related to this concept.

Question 4

Write a nuclear equation to describe the spontaneous fission of  Am to form I-134 and Mo-107. Determine how many neutrons are produced in the reaction.

Accepted Answer

The nuclear equation for the spontaneous fission of Am-243 is:

11ea6923_1859_c77f_80d0_9f61437142b8_TB6105_11 Am --> 2(54_1_131) I + 3(42_1_107) Mo + 4n

This means that one Am-243 nucleus spontaneously fissions into two I-131 nuclei, three Mo-107 nuclei, and four neutrons. Therefore, the number of neutrons produced in the reaction is 4. The correct answer is D) 3.

Question 5

An archaeologist graduate student found a leg bone of a large animal during the building of a new science building.The bone had a carbon-14 decay rate of 14.8 disintegrations per minute per gram of carbon.Living organisms have a decay rate of 15.3 disintegrations per minute.How old is the bone?

Accepted Answer

The formula for calculating the age of the bone is: 
Age = -ln (number of remaining carbon-14/N0) x (1/0.693) x (1/λ)
where N0 is the initial amount of carbon-14, λ is the decay constant, and ln is the natural logarithm.

Since the decay rate of the bone is 14.8 disintegrations per minute per gram of carbon, we can use this to calculate the remaining amount of carbon-14 in the bone compared to the initial amount in a living organism.

14.8/15.3 = 0.9673

This means that the bone has 96.73% of the original amount of carbon-14.

Plugging in the values into the formula, we get: 
Age = -ln (0.9673) x (1/0.693) x (1/0.00012)
Age = 275 years.

Therefore, the bone is approximately 275 years old.

Question 6

Define mass defect.

Accepted Answer

Mass defect is defined as the difference in mass between an atom and the sum of its separate components, which include protons, neutrons and electrons. It is caused by the strong nuclear force, which is responsible for binding nuclear particles together in the nucleus. The mass defect is converted into energy during nuclear reactions, as described by Einstein's famous equation, E=mc². It is an important concept in nuclear physics and is used to calculate the binding energy of nucleons in the nucleus.

Question 7

The following reaction represents what nuclear process?  U +  n →  Ba +  Kr + 3  n

Accepted Answer

The reaction represents nuclear fission, where a uranium nucleus is split into two smaller nuclei (barium and krypton) and three neutrons are released.

Question 8

A geological sample is found to have a Pb-206/U-238 mass ratio of 0.337/1.00.Assuming there was no Pb-206 present when the sample was formed,how old is it? The half-life of U-238 is 4.5 × 10⁹ years.

Accepted Answer

The answer of A geological sample is found to have...

Question 9

Iodine-131 undergoes beta emission with a half-life of 8.02 days.If you start with 44.3 mg of the material,how long will it take for the amount of iodine-131 to drop to 15.3 mg?

Accepted Answer

This is a half-life problem, where we need to find the time it takes for a certain amount of the radioactive substance to decay.

Using the half-life of iodine-131 and the initial amount, we can set up the following equation:

44.3 mg * (1/2)^(t/8.02) = 15.3 mg

Solving for t, we get:

t = 12.3 days

Therefore, the answer is B.

Question 10

Calculate the mass defect in Fe-56 if the mass of an Fe-56 nucleus is 55.921 amu.The mass of a proton is 1.00728 amu and the mass of a neutron is 1.008665 amu.

Accepted Answer

The answer of Calculate the mass defect in Fe-56 if...

Question 11

Write a nuclear equation to describe the neutron induced fission of U-235 to form Xe-134 and Sr-100.Determine how many neutrons are produced in the reaction.

Accepted Answer

The nuclear equation for the neutron induced fission of U-235 is:

U-235 + n --> Xe-134 + Sr-100 + 2n

This means that one neutron (n) is absorbed by U-235 to form Xe-134 and Sr-100, and two neutrons are produced as a result of the fission process. Therefore, the total number of neutrons produced in the reaction is 2.

The best choice is E, which correctly identifies the number of neutrons produced in the reaction.

Question 12

The age of an ancient tree trunk is estimated using radiocarbon dating.If the trunk has a C-14 decay rate that is 34% of what it is in living plants,how old is the trunk? The half-life of C-14 is 5730 years.

Accepted Answer

The answer of The age of an ancient tree trunk...

Question 13

Fluorine-18 undergoes positron emission with a half-life of 1.10 × 10² minutes.If a patient is given a 248 mg dose for a PET scan,how long will it take for the amount of fluorine-18 to drop to 83 mg? (Assume that none of the fluorine is excreted from the body.)

Accepted Answer

The answer of Fluorine-18 undergoes positron emission with a half-life...

Question 14

The nuclide As-76 has a half-life of 26.0 hours.If a sample of As-76 weighs 344 g,what mass of As-76 remains after 538 minutes?

Accepted Answer

First, we need to convert the time given (538 minutes) into hours:

538 min ÷ 60 min/h = 8.97 h

Next, we can use the half-life of As-76 to calculate the fraction of the original sample that remains:

t1/2 = 26.0 h

t = 8.97 h

N/N0 = (1/2)^(t/t1/2)

N/N0 = (1/2)^(8.97/26.0)

N/N0 = 0.274

This means that only 27.4% of the original As-76 sample remains after 538 minutes.

To find the mass of the remaining sample, we can multiply the original mass by this fraction:

Mass remaining = 344 g x 0.274

Mass remaining = 94.304 g

However, we need to round off our answer to three significant figures (since 344 g has three significant figures). The closest choice is B: 271 g.

Question 15

Determine the binding energy of an O-16 nucleus.The O-16 nucleus has a mass of 15.9905 amu.A proton has a mass of 1.00728 amu,a neutron has a mass of 1.008665 amu,and 1 amu is equivalent to 931 MeV of energy.

Accepted Answer

The binding energy of a nucleus can be calculated using the formula: $$BE = \left( Zm_p + Nm_n - M \right) \times 931 \, \text{MeV}$$ where $Z$ is the number of protons, $N$ is the number of neutrons, $m_p$ is the mass of a proton, $m_n$ is the mass of a neutron, $M$ is the mass of the nucleus, and 931 MeV is the energy equivalent of 1 amu. For an O-16 nucleus, $Z = 8$ (since it's oxygen), $N = 8$ (since it's O-16, meaning 16 total nucleons minus 8 protons gives 8 neutrons), $m_p = 1.00728 \, \text{amu}$, $m_n = 1.008665 \, \text{amu}$, and $M = 15.9905 \, \text{amu}$. Plugging these values into the formula gives: $$BE = \left( 8 \times 1.00728 + 8 \times 1.008665 - 15.9905 \right) \times 931 = 128 \, \text{MeV}$$

Question 16

Determine the binding energy of an F-19 nucleus.The F-19 nucleus has a mass of 18.99840325 amu.A proton has a mass of 1.00728 amu,a neutron has a mass of 1.008665 amu,and 1 amu is equivalent to 931 MeV of energy.

Accepted Answer

The binding energy of a nucleus is given by the equation:

$E_{binding} = [Z(m_p + m_e) + N(m_n)]c^2 - m_{F-19}c^2$

where $Z$ is the atomic number (number of protons), $N$ is the number of neutrons, $m_p$ and $m_n$ are the masses of a proton and neutron, respectively, $m_{F-19}$ is the mass of the F-19 nucleus, and $c$ is the speed of light.

Using the provided masses, we can calculate:

$E_{binding} = [9(1.00728) + 10(1.008665)](931.5) - 18.99840325(931.5)$

$E_{binding} \approx 143.2$ MeV

Therefore, the best choice is D: 143 MeV.

Question 17

The splitting of the uranium atom is an example of

Accepted Answer

The splitting of uranium atom involves nuclear fission where the nucleus of an atom is split into smaller fragments releasing a tremendous amount of energy.

Question 18

Write a nuclear equation to describe the neutron induced fission of  Pu to form  Kr and  Ce.Determine how many neutrons are produced in the reaction.

Accepted Answer

The answer of Write a nuclear equation to describe the...

Question 19

Give the goal of the Manhattan project.

Accepted Answer

The goal of the Manhattan Project was to build an atomic bomb. The project was initiated during World War II, and the bomb was intended to be used as a powerful weapon against Germany and Japan. The project involved several top scientists and engineers, including Robert Oppenheimer and Enrico Fermi, and resulted in the successful development of the first nuclear weapons.

Question 20

The splitting of a heavy nucleus to form two or more lighter ones is called

Accepted Answer

The process described is nuclear fission, which involves the splitting of a heavy nucleus into two or more lighter nuclei. Choice A, radioactive cleavage, is not a commonly used term in nuclear physics. Choice C, nuclear fusion, involves the joining of two lighter nuclei to form a heavier one. Choice D, radioactive merge, is not a scientifically recognized term. Choice E, half life, refers to the time it takes for half of a radioactive substance to decay, and is not related to nuclear fission.

Quiz 21: Radioactivity and Nuclear Chemistry