$$N = N_0$ \times \left(\frac{1}{2}\right)^n$$

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 in the nucleus.

Question 3

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes are atoms of the same element with 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 for protection?

Accepted Answer

Gamma rays

Question 9

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

Accepted Answer

A neutron is converted into a proton.

Question 10

Which of the following best describes radioactive decay?

Accepted Answer

The spontaneous transformation of an unstable atomic nucleus into a more stable one, often releasing particles or energy.

Question 11

Which equation correctly represents the relationship between the remaining amount of a radioactive substance and the number of half-lives elapsed?

Accepted Answer

$$N = N_0$ 	imes \left(\frac{1}{2}ight)^n$$

Question 12

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

Accepted Answer

Using iodine-131 to treat thyroid disorders.

Question 13

What happens to the atomic number and mass number when an alpha particle is emitted from a nucleus?

Accepted Answer

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

Question 14

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

Accepted Answer

High risk of deep tissue and organ damage

Question 15

Which symbol correctly represents a beta particle?

Accepted Answer

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

Question 16

Which type of nuclear decay does not change the atomic number or mass number of the nucleus?

Accepted Answer

Gamma decay

Question 17

Which of the following best explains how carbon-14 is used in carbon dating?

Accepted Answer

By measuring the ratio of carbon-14 to carbon-12 in a sample to estimate its age.

Question 18

Which of the following is a correct statement about half-life?

Accepted Answer

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

Question 19

Which of the following is a correct description of the change in the nucleus when a positron is emitted?

Accepted Answer

A proton is converted into a neutron.

Question 20

Which of the following is a reason why nuclear radiation can be damaging to life?

Accepted Answer

It can cause mutations in DNA by ionizing molecules in cells.

Introduction to Isotopes, Nuclear Chemistry, and Radioactivity

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