Question 1

Which of the following best describes the difference between an atom and a molecule?

Accepted Answer

An atom is the smallest unit of an element, while a molecule is a group of two or more atoms bonded together.

Question 2

Which of the following is an example of allotropes?

Accepted Answer

Graphite and diamond, both forms of carbon.

Question 3

What is the chemical formula for hydrogen peroxide?

Accepted Answer

$$\mathrm{H_2O_2}$$

Question 4

Why is it dangerous to drink hydrogen peroxide instead of water, even though both contain hydrogen and oxygen?

Accepted Answer

The ratio and arrangement of atoms in hydrogen peroxide make it chemically reactive and harmful to living tissues.

Question 5

Which of the following statements about the scientific approach is correct?

Accepted Answer

A hypothesis is a testable guess, while a theory is a well-supported explanation based on evidence.

Question 6

A student claims that graphite and diamond are different elements because they look and behave differently. What is the best scientific response?

Accepted Answer

Graphite and diamond are allotropes, meaning they are different forms of the same element (carbon) with different atomic arrangements.

Question 7

Which of the following best illustrates the concept that matter is made of atoms and molecules?

Accepted Answer

A balloon filled with helium gas, where each helium atom moves independently.

Question 8

Which of the following is a molecule but not an element?

Accepted Answer

$$\mathrm{H_2O}$$

Question 9

A scientist observes that a certain substance is made of only one type of atom arranged in a 3D pattern. Which substance is this most likely to be?

Accepted Answer

Diamond

Question 10

Which of the following is the best example of a hypothesis?

Accepted Answer

If I increase the temperature of water, then it will evaporate faster.

Question 11

Which of the following is NOT a correct statement about molecules?

Accepted Answer

Molecules are always made of different types of atoms.

Question 12

Which of the following best explains why water and hydrogen peroxide have different properties?

Accepted Answer

They have different ratios of hydrogen to oxygen atoms, resulting in different molecular structures.

Question 13

Which of the following is an example of a theory in science?

Accepted Answer

The atomic theory, which states that all matter is composed of atoms.

Question 14

Which of the following best describes the structure of graphite?

Accepted Answer

Carbon atoms bonded in continuous 2-dimensional sheets.

Question 15

Which of the following is the correct chemical formula for a water molecule?

Accepted Answer

$$\mathrm{H_2O}$$

Question 16

A student proposes that all clear, colorless liquids are water. According to the scientific approach, what is this statement?

Accepted Answer

A hypothesis, because it is a testable guess.

Question 17

Which of the following best describes the difference between a hypothesis and a theory?

Accepted Answer

A hypothesis is a testable guess, while a theory is a well-supported explanation based on evidence.

Question 18

Which of the following is a real-world example of the importance of molecular structure?

Accepted Answer

Graphite is used in pencils because its layers slide easily, while diamond is used in cutting tools because of its hardness.

Question 19

Which of the following best describes why a helium-filled balloon floats in air?

Accepted Answer

Helium atoms are less dense than air, causing the balloon to rise.

Question 20

Which of the following is NOT an example of a molecule?

Accepted Answer

$$\mathrm{He}$$

Chapter 1: Matter, Measurement, and Problem Solving – Atoms, Molecules, and the Scientific Approach

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