Question 1

Which of the following statements correctly describes the difference between isotopes of the same element?

Accepted Answer

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

Question 2

A neutral atom of carbon-14 is represented as $$\displaystyle \frac{14}{6}	ext{C}. $$How many neutrons does this atom have?

Accepted Answer

8

Question 3

Which of the following forms of nuclear radiation is the most penetrating and can pass completely through the human body?

Accepted Answer

Gamma ($$\gamma) $$rays

Question 4

What is the main reason x-rays are NOT considered a form of nuclear radiation?

Accepted Answer

X-rays are produced by changes in electron energy levels, not the nucleus.

Question 5

A radioactive isotope undergoes alpha decay. Which of the following correctly describes the change in its atomic and mass numbers?

Accepted Answer

The atomic number decreases by 2 and the mass number decreases by 4.

Question 6

Which of the following best describes the atomic mass (atomic weight) of an element as listed on the periodic table?

Accepted Answer

It is the weighted average of the masses of all naturally occurring isotopes of the element.

Question 7

Which of the following statements about natural background radiation is TRUE?

Accepted Answer

It is radiation that comes from natural sources such as cosmic rays and radioactive elements in the earth.

Question 8

A patient receives a PET scan using a tracer containing fluorine-18 ($$^{18}F). $$What type of nuclear emission is primarily responsible for the imaging signal detected?

Accepted Answer

Gamma ($$\gamma) $$rays produced after positron emission and annihilation with an electron.

Question 9

Which of the following units is used to measure the biological effect of radiation exposure?

Accepted Answer

Sievert (Sv)

Question 10

If a radioactive sample has a half-life of 2 days, what fraction of the original sample remains after 6 days?

Accepted Answer

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

Question 11

Which of the following best explains why gamma emitters are preferred for imaging in nuclear medicine?

Accepted Answer

Gamma rays can exit the body and be detected by external sensors, providing clear images.

Question 12

Which of the following statements about alpha ($$\alpha) $$particles is correct?

Accepted Answer

They consist of 2 protons and 2 neutrons and have a $$+2$$ charge.

Question 13

A radioactive isotope emits a beta ($$\beta) $$particle. What happens to its atomic number and mass number?

Accepted Answer

The atomic number increases by 1; the mass number remains unchanged.

Question 14

Why is it important for workers handling radioactive materials to wear a dosimeter or film badge?

Accepted Answer

To monitor and record their cumulative exposure to ionizing radiation.

Question 15

Which of the following is a correct symbolic representation for an isotope of carbon with 7 neutrons?

Accepted Answer

$$\displaystyle \frac{13}{6}	ext{C}$$

Question 16

Which of the following statements about the half-life of a radioisotope is TRUE?

Accepted Answer

It is the time required for half of the radioactive atoms in a sample to decay.

Question 17

Which of the following types of nuclear radiation is most likely to be stopped by a sheet of paper or the outer layer of skin?

Accepted Answer

Alpha ($$\alpha) $$particles

Question 18

A sample of a radioisotope is measured to have an activity of 2.0 millicuries (mCi). Which of the following best describes what this measurement means?

Accepted Answer

The sample undergoes a certain number of nuclear disintegrations per second.

Question 19

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

Accepted Answer

Using technetium-99m ($$^{99m}Tc) as a $$gamma emitter for imaging organs.

Question 20

Which of the following best explains why different radioisotopes are chosen for different medical imaging procedures?

Accepted Answer

Their half-lives and types of radiation emitted determine their suitability for specific diagnostic purposes.

Atoms and Radioactivity: Study Guide for GOB Chemistry Chapter 2

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