$$k = \frac{0.693}{4.51 \times 10^9$}$$

Question 1

Which of the following physical forces is primarily responsible for holding protons and neutrons together in the nucleus?

Accepted Answer

Strong nuclear force

Question 2

A nuclide of element X has atomic number $$Z = 20$$ and mass number $$A = 45. $$How many neutrons does it contain?

Accepted Answer

$$25$$

Question 3

Which type of radioactive decay results in the emission of a particle with the same mass as an electron but with a positive charge?

Accepted Answer

Positron emission (Beta-plus decay)

Question 4

What is the correct nuclear equation for the beta-minus decay of $$^{14}_{6}C$$?

Accepted Answer

$$^{14}_{6}C \$$rightarrow ^{14}$$_{7}N + 0_{-1}e$$

Question 5

Which statement best describes the 'belt of stability' for nuclides?

Accepted Answer

It is the region where nuclides have a stable ratio of neutrons to protons, depending on atomic number.

Question 6

A radioactive isotope has a half-life of $$4.51 	imes 10^9$ years. What is its decay constant k$?

Accepted Answer

$$k = \frac{0.693}{4.51 	imes 10^9$}$$

Question 7

Which decay process increases the atomic number of a nuclide by one while keeping the mass number the same?

Accepted Answer

Beta-minus decay

Question 8

If a nuclide is above the belt of stability, which decay mode is it most likely to undergo?

Accepted Answer

Beta-minus decay

Question 9

Which of the following best explains why only 279 out of ~2000 known nuclides are stable with respect to radioactive decay?

Accepted Answer

Stable nuclides have a balanced neutron-to-proton ratio and sufficient nuclear binding energy.

Question 10

Which equation correctly represents the first-order kinetics of radioactive decay?

Accepted Answer

$$\ln \left( \frac{N}{N_0$} \right) = -kt$$

Question 11

During carbon-14 dating, what happens to the $$^{14}C$$/^{12}$$C$$ ratio in an organism after it dies?

Accepted Answer

It decreases over time as $$^{14}C$$ decays and is not replenished.

Question 12

Which of the following is true about alpha decay?

Accepted Answer

It decreases the mass number by four and atomic number by two.

Question 13

A nuclide $$^{A}_{Z}X$$ undergoes positron emission. What is the resulting nuclide?

Accepted Answer

$$^{A}_{Z-1}Y$$

Question 14

Which of the following is a correct statement about electron capture?

Accepted Answer

It decreases the atomic number by one.

Question 15

Which of the following nuclides is most likely to undergo alpha decay?

Accepted Answer

A nuclide with a very high atomic number and mass number.

Question 16

What is the primary reason for the emission of gamma radiation during nuclear decay?

Accepted Answer

To allow the nucleus to transition from an excited state to a lower energy state.

Question 17

Which of the following best describes the change in the number of protons and neutrons during beta-minus decay?

Accepted Answer

A neutron is converted into a proton, increasing the atomic number by one.

Question 18

If a nuclide is below the belt of stability, which decay mode is it most likely to undergo?

Accepted Answer

Beta-plus decay or electron capture

Question 19

Which of the following is the correct expression for the half-life $$t_{1/2} in $$terms of the decay constant $$k$$?

Accepted Answer

$$t_{1/2} = \frac{0.693}{k}$$

Question 20

Which of the following best describes the process of radiocarbon dating?

Accepted Answer

It measures the ratio of $$^{14}C to$$ $$^{12}C in a $$sample to estimate its age.

Nuclear Chemistry: Forces, Decay, Stability, and Kinetics

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