Question 1

Which of the following best defines an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 2

A nucleus of chlorine contains 17 protons and 20 neutrons. What is its nuclear symbol?

Accepted Answer

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

Question 3

Which factor most directly determines the stability of an atom?

Accepted Answer

The ratio of neutrons to protons.

Question 4

If a nucleus of uranium has a mass number of 238, how many neutrons does it contain?

Accepted Answer

146

Question 5

Which of the following statements about radioactive decay is correct?

Accepted Answer

Radioactive decay is a process by which unstable nuclei lose energy by emitting radiation.

Question 6

What is the half-life of a radioactive isotope?

Accepted Answer

The time it takes for half of the atoms in a sample to decay.

Question 7

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

Accepted Answer

12.5 g

Question 8

Which type of radiation requires the heaviest shielding for protection?

Accepted Answer

Gamma radiation

Question 9

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

Accepted Answer

A neutron is converted into a proton.

Question 10

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

Accepted Answer

Using iodine-131 to diagnose and treat thyroid disorders.

Question 11

A sample of radium-226 has a half-life of 1600 years. How many grams of a 2.00 g sample will remain after three half-lives?

Accepted Answer

0.25 g

Question 12

Which of the following best describes alpha decay?

Accepted Answer

Emission of a helium nucleus ($$\mathrm{^{4}_{2}He}) $$from the nucleus.

Question 13

What happens to the atomic number and mass number when a gamma ray is emitted from a nucleus?

Accepted Answer

Both atomic number and mass number stay the same.

Question 14

Which of the following is a risk associated with exposure to ionizing radiation?

Accepted Answer

Increased risk of genetic mutations and cancer.

Question 15

Which symbol correctly represents a beta particle?

Accepted Answer

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

Question 16

Carbon-14 decays to nitrogen-14 by emitting which particle?

Accepted Answer

Beta particle

Question 17

Which of the following statements about nuclear fission in power plants is correct?

Accepted Answer

It involves the splitting of heavy nuclei such as uranium-235.

Question 18

Which of the following is true about the use of isotopes in carbon dating?

Accepted Answer

Carbon-14 decays at a known rate, allowing scientists to estimate the age of organic materials.

Question 19

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

Accepted Answer

A proton is converted into a neutron.

Question 20

Which of the following is a correct statement about the dangers of radon gas?

Accepted Answer

Radon gas is a radioactive element that can increase the risk of lung cancer when inhaled.

Isotopes, Nuclear Chemistry, and Radioactivity: Study Guide

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