Q: A sample contains 5.0 mCi of phosphorus-32. How many microcuries ($\mu$Ci) does this represent? ($1\ \mathrm{mCi} = 1000\ \mu\mathrm{Ci}$)

$5.0 \times 1000 = 5000\ \mu\mathrm{Ci}$

Question 1

Which subatomic particle is responsible for the identity of an element, and what is its charge?

Accepted Answer

Proton; positive charge

Question 2

A neutral atom of phosphorus has an atomic number of 15 and a mass number of 31. How many neutrons does it have?

Accepted Answer

$31 - 15 = 16$ neutrons

Question 3

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 4

Which type of radiation is most penetrating and requires dense materials like lead or concrete for shielding?

Accepted Answer

Gamma rays

Question 5

A radioactive isotope has a half-life of 8 hours. If you start with 100 mg, how much remains after 24 hours?

Accepted Answer

$100 \div 2^3 = 12.5$ mg

Question 6

Which of the following nuclear equations correctly represents alpha decay of radon-222 ($^{222}_{86}\mathrm{Rn}$)?

Accepted Answer

$^{222}_{86}\mathrm{Rn} \rightarrow ^{218}_{84}\mathrm{Po} + ^{4}_{2}\mathrm{He}$

Question 7

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

Accepted Answer

It can eject electrons from atoms, potentially damaging biological tissue.

Question 8

A sample contains 5.0 mCi of phosphorus-32. How many microcuries ($\mu$Ci) does this represent? ($1\ \mathrm{mCi} = 1000\ \mu\mathrm{Ci}$)

Accepted Answer

$5.0 	imes 1000 = 5000\ \mu\mathrm{Ci}$

Question 9

Which type of radioactive decay results in the emission of a high-energy electron from the nucleus?

Accepted Answer

Beta decay

Question 10

A hospital needs to administer a radioactive isotope with a half-life of 6 hours for imaging. If the initial dose is 24 mCi, how much activity remains after 18 hours?

Accepted Answer

$24 \div 2^3 = 3$ mCi

Question 11

Which of the following is a correct statement about the atomic mass unit (amu)?

Accepted Answer

1 amu is defined as exactly one-twelfth the mass of a carbon-12 atom.

Question 12

Which of the following is NOT a property of gamma radiation?

Accepted Answer

It can be stopped by a sheet of paper.

Question 13

A PET scan uses which type of radioactive emission to produce images?

Accepted Answer

Positron emission

Question 14

Which of the following best explains why rapidly dividing cells are more affected by radiation therapy?

Accepted Answer

They are more likely to absorb radiation due to increased metabolic activity.

Question 15

Which of the following is the correct symbol for a beta particle?

Accepted Answer

$^{0}_{-1}\mathrm{e}$

Question 16

If a neutral atom has 17 protons, 18 neutrons, and 17 electrons, what is its atomic number and mass number?

Accepted Answer

Atomic number = 17, Mass number = 35

Question 17

Which of the following best describes the process of radioactive decay?

Accepted Answer

An unstable nucleus emits radiation and transforms into a new nucleus.

Question 18

Which shielding material is most effective for stopping alpha particles?

Accepted Answer

A sheet of paper

Question 19

Which SI unit is used to measure the number of radioactive disintegrations per second?

Accepted Answer

Becquerel ($\mathrm{Bq}$)

Question 20

A radioactive isotope used in medicine has a physical half-life of 3 hours and a biological half-life of 6 hours. Which of the following best describes its effective half-life?

Accepted Answer

It is shorter than either the physical or biological half-life.

Atoms, Atomic Structure, Isotopes, and Radioactivity – Chapter 2 Study Notes

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