Question 1

Which of the following best defines an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 2

What determines the stability of an atom?

Accepted Answer

The ratio of neutrons to protons.

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

What is the nuclear symbol for a chlorine atom with 17 protons and 20 neutrons?

Accepted Answer

$$\mathrm{^{37}_{17}Cl}$$

Question 5

A nucleus of uranium has a mass number of 238. How many neutrons does it contain if its atomic number is 92?

Accepted Answer

146

Question 6

Given a sample of radium-226 with a half-life of 1600 years, how much of a 2.00 gram sample will remain after three half-lives?

Accepted Answer

0.25 grams

Question 7

A 100 g sample of a radioactive isotope has a half-life of 8 days. After 24 days, how much of the isotope remains?

Accepted Answer

12.5 g

Question 8

Which type of radiation requires the heaviest shielding?

Accepted Answer

Gamma rays, because they have no mass and are highly penetrating.

Question 9

What happens to the atomic number and mass number of a nucleus when it emits an alpha particle?

Accepted Answer

Atomic number decreases by 2, mass number decreases by 4.

Question 10

Which equation correctly represents the decay of $$\mathrm{^{14}_{6}C} by $$beta emission?

Accepted Answer

$$\mathrm{^{14}_{6}C \$$rightarrow ^{14}$$_{7}N + \beta^-}$$

Question 11

Which of the following best describes 'half-life'?

Accepted Answer

The time required for half of a radioactive sample to decay.

Question 12

When a beta particle ($$\beta^-) is $$released from an unstable nucleus, what change occurs?

Accepted Answer

A neutron is converted into a proton.

Question 13

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

Accepted Answer

Using radioactive tracers for imaging and cancer treatment.

Question 14

Which type of radioactive emission does NOT change the atomic number or mass number of the nucleus?

Accepted Answer

Gamma emission

Question 15

What is the main risk associated with exposure to gamma radiation?

Accepted Answer

Internal organ damage due to deep penetration

Question 16

Which of the following best explains how carbon dating works?

Accepted Answer

By measuring the ratio of $$\mathrm{^{14}C} to$$ $$\mathrm{^{12}C} in a $$sample and using the known half-life of $$\mathrm{^{14}C}.$$

Question 17

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

Accepted Answer

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

Question 18

If a radioactive isotope undergoes three half-lives, what fraction of the original sample remains?

Accepted Answer

$$\dfrac{1}{8}$$

Question 19

Which of the following statements about alpha particles is correct?

Accepted Answer

Alpha particles are easily stopped by paper or skin.

Question 20

Which of the following is a potential environmental risk of radon gas?

Accepted Answer

Radon gas can lead to increased risk of lung cancer due to its radioactive decay.

Isotopes, Nuclear Chemistry, and Radioactive Decay: Study Guide

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