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 carbon has an atomic number of 6 and a mass number of 14. How many neutrons does it contain?

Accepted Answer

8

Question 3

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 4

Given the atomic mass of carbon is 12.0107 amu, which isotope is most abundant in nature?

Accepted Answer

Carbon-12

Question 5

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

Accepted Answer

Gamma radiation

Question 6

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

Accepted Answer

12.5 mg

Question 7

Which equation correctly represents the relationship between atomic number ($$Z$$), mass number ($$A$$), and number of neutrons ($$N) in an $$atom?

Accepted Answer

$$N = A - Z$$

Question 8

Which of the following is a real-world application of a radioisotope in medicine?

Accepted Answer

Using iodine-131 to treat thyroid disorders

Question 9

Which particle is emitted during beta decay?

Accepted Answer

An electron

Question 10

If a sample contains 5.0 mCi of phosphorous-32, how many mCi are present after two half-lives?

Accepted Answer

1.25 mCi

Question 11

Which of the following statements about alpha particles is correct?

Accepted Answer

They consist of two protons and two neutrons

Question 12

What is the SI unit for the number of radioactive disintegrations per second?

Accepted Answer

Becquerel (Bq)

Question 13

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

Accepted Answer

Radiation damages DNA, and rapidly dividing cells are less able to repair it before dividing

Question 14

A PET scan uses which type of emission to visualize metabolic activity in tissues?

Accepted Answer

Positron emission

Question 15

Which of the following is true about the mass of an electron compared to a proton?

Accepted Answer

Electron is about 1/2000 the mass of a proton

Question 16

Which shielding material is most effective against beta radiation?

Accepted Answer

Aluminum

Question 17

If a radioactive isotope has a half-life of 3 days, how long will it take for only 1/8 of the original sample to remain?

Accepted Answer

9 days

Question 18

Which of the following is NOT a natural source of radiation?

Accepted Answer

Medical X-rays

Question 19

Which equation represents the decay of a radioactive isotope emitting an alpha particle?

Accepted Answer

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

Question 20

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

Accepted Answer

1 amu is defined as 1/12 the mass of a carbon-12 atom

Atoms, Isotopes, and Radioactivity: Chapter 2 Study Notes

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