Question 1

A sample of an unknown substance is shiny, conducts electricity, and can be drawn into wires. It is found to contain only one type of atom. Which classification best describes this substance?

Accepted Answer

Element

Question 2

Which of the following is an example of an intensive property?

Accepted Answer

Density

Question 3

A chemist separates a mixture of sand and iron filings by using a magnet. Which property is being used to separate the mixture?

Accepted Answer

Magnetism

Question 4

Which of the following statements correctly distinguishes between a compound and an element?

Accepted Answer

A compound can be broken down into simpler substances by chemical means, while an element cannot.

Question 5

A 15.0 g sample of a metal occupies 1.20 cm³. What is the density of the metal?

Accepted Answer

12.5 g/cm³

Question 6

Which of the following changes is an example of an endothermic process?

Accepted Answer

Ice melting

Question 7

A student is given a clear, colorless liquid. She evaporates the liquid and finds a white residue remains. Which classification best describes the original sample?

Accepted Answer

Homogeneous mixture (solution)

Question 8

Which of the following is a correct statement about the law of conservation of energy?

Accepted Answer

Energy can neither be created nor destroyed, only transformed.

Question 9

How many atoms are present in 3.50 moles of neon (Ne)? (Avogadro's number = 6.02 × 10²³)

Accepted Answer

2.11 × 10²⁴ atoms

Question 10

Which of the following best describes an alloy such as brass?

Accepted Answer

A homogeneous mixture of metals

Question 11

A solid cylinder has a radius of 2.0 cm and a height of 5.0 cm. What is its volume? (Use π ≈ 3.14)

Accepted Answer

62.8 cm³

Question 12

Which of the following is an example of a chemical property?

Accepted Answer

Reactivity with water

Question 13

Which process would best separate a mixture of ethanol (boiling point 78°C) and water (boiling point 100°C)?

Accepted Answer

Distillation

Question 14

Which of the following is an example of a diatomic element?

Accepted Answer

Oxygen (O₂)

Question 15

A sample of a substance is found to have a mass of 50.0 g and a volume of 62.5 mL. What is its density?

Accepted Answer

0.80 g/mL

Question 16

Which of the following best describes the difference between a homogeneous and a heterogeneous mixture?

Accepted Answer

Homogeneous mixtures have uniform composition throughout, while heterogeneous mixtures do not.

Question 17

How many grams are in 4.00 × 10²³ atoms of magnesium? (Mg atomic mass ≈ 24.3 g/mol)

Accepted Answer

16.2 g

Question 18

Which of the following is an example of an allotrope?

Accepted Answer

O₂ and O₃ (oxygen and ozone)

Question 19

A 250 mL sample of a liquid has a mass of 200 g. What is the density of the liquid in g/mL?

Accepted Answer

0.80 g/mL

Question 20

Which of the following best explains why the properties of sodium chloride (NaCl) are different from those of sodium and chlorine?

Accepted Answer

NaCl is a compound, and compounds have properties different from their constituent elements.

Introduction to Matter, Classification, and Basic Quantitative Concepts in Chemistry

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