Question 1

Which statement best describes the main difference between Dalton's atomic theory and the earlier Greek philosophical ideas about matter?
Correct answer: Dalton's theory was based on experimental evidence, while Greek ideas were philosophical.

Accepted Answer

Dalton's theory was based on experimental evidence, while Greek ideas were philosophical.

Question 2

A neutral atom of element X has 17 protons, 18 neutrons, and 17 electrons. What is the mass number (A) and atomic number (Z) of this atom?
Correct answer: A = 35, Z = 17

Accepted Answer

A = 35, Z = 17

Question 3

Which of the following best explains why the atomic mass of chlorine listed on the periodic table is not a whole number?
Correct answer: It is a weighted average of the masses of all naturally occurring isotopes of chlorine.

Accepted Answer

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

Question 4

A sample of silicon contains 92.2% 28Si (mass = 27.977 u), 4.7% 29Si (mass = 28.976 u), and 3.1% 30Si (mass = 29.974 u). What is the average atomic mass of silicon? (Round to two decimal places.)
Correct answer: 28.09 u

Accepted Answer

28.09 u

Question 5

Which of the following scenarios would violate the law of conservation of mass as described by Lavoisier?
Correct answer: A chemical reaction in which the total mass of products is less than the total mass of reactants.

Accepted Answer

A chemical reaction in which the total mass of products is less than the total mass of reactants.

Question 6

Which statement about isotopes is correct?
Correct answer: Isotopes of an element have the same number of protons but different numbers of neutrons.

Accepted Answer

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

Question 7

A forensic scientist uses mass spectrometry to analyze a tooth sample and finds a high ratio of 14C to 12C. What can be inferred from this result?
Correct answer: The individual likely died recently, as 14C decays over time.

Accepted Answer

The individual likely died recently, as 14C decays over time.

Question 8

Which of the following best describes the location and relative mass of subatomic particles in an atom?
Correct answer: Protons and neutrons are in the nucleus and account for most of the atom's mass; electrons orbit the nucleus and have negligible mass.

Accepted Answer

Protons and neutrons are in the nucleus and account for most of the atom's mass; electrons orbit the nucleus and have negligible mass.

Question 9

If an atom has 12 protons, 13 neutrons, and 10 electrons, what is its overall charge and what is the name of this species?
Correct answer: Charge = +2; it is a cation.

Accepted Answer

Charge = +2; it is a cation.

Question 10

Which of the following is a direct application of Proust's law of definite proportions?
Correct answer: Water from any source always contains hydrogen and oxygen in a 2:1 ratio by atom.

Accepted Answer

Water from any source always contains hydrogen and oxygen in a 2:1 ratio by atom.

Question 11

A student claims that atoms can be created or destroyed in a chemical reaction. Which scientific law directly contradicts this claim?
Correct answer: Law of conservation of mass

Accepted Answer

Law of conservation of mass

Question 12

Which of the following best explains why mass spectrometry is useful in biological research?
Correct answer: It allows scientists to determine the isotopic composition of elements in biological samples.

Accepted Answer

It allows scientists to determine the isotopic composition of elements in biological samples.

Question 13

Which of the following would be considered a mixture of isotopes?
Correct answer: A naturally occurring sample of oxygen gas (O2)

Accepted Answer

A naturally occurring sample of oxygen gas (O2)

Question 14

If a neutral atom of element Y has an atomic number of 20 and a mass number of 42, how many neutrons does it have?
Correct answer: 22

Accepted Answer

22

Question 15

Which of the following statements is inconsistent with Dalton's atomic theory as originally proposed?
Correct answer: Atoms of the same element can have different masses.

Accepted Answer

Atoms of the same element can have different masses.

Question 16

A scientist is analyzing a sample and finds that the ratio of two isotopes of lead is different from the natural abundance. Which process could most likely explain this observation?
Correct answer: The sample has undergone radioactive decay over time.

Accepted Answer

The sample has undergone radioactive decay over time.

Question 17

Which of the following best describes the relationship between atomic number and chemical identity?
Correct answer: The atomic number determines the element's identity because it equals the number of protons.

Accepted Answer

The atomic number determines the element's identity because it equals the number of protons.

Question 18

Which of the following real-world applications relies on the concept of isotopes?
Correct answer: Using 14C dating to estimate the age of archaeological artifacts.

Accepted Answer

Using 14C dating to estimate the age of archaeological artifacts.

Question 19

A sample contains 80% isotope A (mass = 10 u) and 20% isotope B (mass = 11 u). What is the average atomic mass of the element?
Correct answer: 10.2 u

Accepted Answer

10.2 u

Foundations of Atomic Structure and Isotopes

Study Guide - Practice Questions

Study Guide - Flashcards