Q: Which of the following equations is used to calculate the fraction of a radioactive isotope remaining after $$n$$ half-lives?

$$ \text{fraction remaining} = 0.5^n $$

Question 1

Which of the following statements best describes the difference between nuclear reactions and chemical reactions?

Accepted Answer

Nuclear reactions involve changes in the nucleus and can result in the transformation of one element into another, while chemical reactions involve only the rearrangement of electrons and do not change the identity of elements.

Question 2

Which equation correctly represents the alpha decay of uranium-238?

Accepted Answer

$$ \mathrm{^{238}_{92}U \$$rightarrow ^{234}$$_{90}Th $$+ ^{4}$$_{2}He} $$

Question 3

A radioactive isotope has a half-life of 10 years. What fraction of the original sample remains after 30 years?

Accepted Answer

$$ \frac{1}{8} $$

Question 4

Which type of radiation consists of high-energy electromagnetic waves and has no mass or charge?

Accepted Answer

Gamma radiation

Question 5

What is the balanced nuclear equation for the beta decay of carbon-14?

Accepted Answer

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

Question 6

Which of the following best describes the process of positron emission?

Accepted Answer

A proton is converted into a neutron and a positron, and the positron is emitted.

Question 7

If the intensity of radiation at a distance $$d_1 is$$ $$I_1$$, what is the intensity $$I_2 at a $$distance $$d_2$$ from the same source?

Accepted Answer

$$ I_2$ = I_1$ \left( \frac{d_1$}{d_2$} \$$right)^2$$ $$

Question 8

Which of the following is a correct representation of the positron?

Accepted Answer

$$ ^{0}_{+1}e $$

Question 9

Which of the following statements about artificial transmutation is correct?

Accepted Answer

It involves bombarding a nucleus with a particle to induce a nuclear reaction.

Question 10

Which equation represents the fission of uranium-235 when bombarded with a neutron?

Accepted Answer

$$ \mathrm{^{235}_{92}U $$+ ^{1}$$_{0}n \$$rightarrow ^{139}$$_{56}Ba $$+ ^{94}$$_{36}Kr + 3\ ^{1}_{0}n} $$

Question 11

A sample of a radioactive isotope has decayed to 12.5% of its original amount. How many half-lives have elapsed?

Accepted Answer

4

Question 12

Which of the following best describes the biological effect of ionizing radiation?

Accepted Answer

It can knock out an electron from an atom, converting the atom into a highly reactive ion.

Question 13

Which device is commonly used to detect and measure the intensity of radiation in a laboratory setting?

Accepted Answer

Geiger counter

Question 14

Which of the following equations is used to calculate the fraction of a radioactive isotope remaining after $$n$$ half-lives?

Accepted Answer

$$ 	ext{fraction remaining} = 0.5^n $$

Question 15

Which of the following types of radiation is most likely to be stopped by a sheet of paper?

Accepted Answer

Alpha radiation

Question 16

Which of the following is the correct equation for Einstein's mass-energy equivalence?

Accepted Answer

$$ E = mc^2$ $$

Question 17

Which of the following best describes the process of gamma emission?

Accepted Answer

A nucleus emits a high-energy photon without changing its atomic number or mass number.

Question 18

Which of the following is a correct balanced equation for the artificial transmutation of plutonium-239 by bombardment with an alpha particle?

Accepted Answer

$$ \mathrm{^{239}_{94}Pu $$+ ^{4}$$_{2}He \$$rightarrow ^{242}$$_{96}Cm $$+ ^{1}$$_{0}n} $$

Question 19

Which of the following best explains why rapidly dividing cancer cells are more susceptible to radiation therapy?

Accepted Answer

They are less likely to repair DNA damage caused by ionizing radiation.

Chapter 11: Nuclear Chemistry – Study Notes

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