Question 1

Which statement best describes isotopes of an element?

Accepted Answer

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

Question 2

Chlorine has two naturally occurring isotopes: $^{35}Cl$ and $^{37}Cl$. If the atomic mass of chlorine is 35.45 amu, which isotope is more abundant?

Accepted Answer

$^{35}Cl$ is more abundant because the atomic mass is closer to 35 amu.

Question 3

Which of the following nuclear reactions represents alpha decay?

Accepted Answer

$^{238}U \rightarrow ^{234}Th + \alpha$

Question 4

During beta decay, what happens to the atomic number and mass number of the parent nucleus?

Accepted Answer

Atomic number increases by 1; mass number remains unchanged.

Question 5

Which isotope of hydrogen is radioactive and used in nuclear reactors?

Accepted Answer

Tritium ($^3H$)

Question 6

What is the result of electron capture in $^{7}Be$?

Accepted Answer

$^{7}Be + e^{-} \rightarrow ^{7}Li$

Question 7

Which radioactive decay process does NOT change the atomic number or mass number of the nucleus?

Accepted Answer

Gamma emission

Question 8

A sample of uranium contains $^{238}U$ and $^{235}U$. Why is $^{235}U$ important in nuclear reactors?

Accepted Answer

$^{235}U$ undergoes fission more readily, releasing energy for nuclear reactions.

Question 9

Which equation correctly represents positron emission?

Accepted Answer

$^{11}C \rightarrow ^{11}B + e^{+}$

Question 10

If a nucleus undergoes alpha decay, how do its atomic number ($Z$) and mass number ($A$) change?

Accepted Answer

$Z$ decreases by 2, $A$ decreases by 4

Question 11

Which of the following is true about the mass number ($A$) and atomic number ($Z$) in a balanced nuclear reaction?

Accepted Answer

The sum of $A$ and $Z$ of the reactants equals the sum of $A$ and $Z$ of the products.

Question 12

Carbon-14 ($^{14}C$) is used in radiocarbon dating. Which decay process does it undergo?

Accepted Answer

Beta decay

Question 13

Which of the following best explains why isotopes of an element have nearly identical chemical properties?

Accepted Answer

Because they have the same number of protons and electrons.

Question 14

What is the effect of beta decay on the neutron and proton count of a nucleus?

Accepted Answer

A neutron is converted into a proton.

Question 15

Which process is described by the equation $^{7}Be + e^{-} \rightarrow ^{7}Li + \gamma$?

Accepted Answer

Electron capture

Question 16

Which of the following statements about gamma emission is correct?

Accepted Answer

It does not change either the atomic number or the mass number.

Question 17

Which isotope is used to date archaeological samples and why?

Accepted Answer

$^{14}C$ because it is radioactive and decays at a known rate.

Question 18

Which of the following is a correct representation of the atomic number ($Z$) and mass number ($A$) for an element?

Accepted Answer

$A$ is the number of protons plus neutrons; $Z$ is the number of protons.

Question 19

Which nuclear process is responsible for the emission of a positron?

Accepted Answer

Positron emission

Atoms, Isotopes, and Nuclear Chemistry: Study Notes

Study Guide - Practice Questions