Question 1

Which of the following best describes a chemical change?

Accepted Answer

Burning magnesium ribbon in air to form magnesium oxide

Question 2

Which separation technique would be most effective for separating a mixture of sand and salt water?

Accepted Answer

Filtration

Question 3

Which statement correctly distinguishes between a compound and a mixture?

Accepted Answer

A compound has a fixed composition and can only be separated by chemical means, while a mixture can be separated by physical means.

Question 4

Which of the following is an example of a homogeneous mixture?

Accepted Answer

Air

Question 5

A student wants to separate a mixture of iron filings and sulfur powder. Which physical property should they use and what method is most appropriate?

Accepted Answer

Magnetism; use of a magnet

Question 6

Which of the following is a pure substance?

Accepted Answer

Copper metal

Question 7

Which of the following best describes an element?

Accepted Answer

A pure substance that cannot be broken down by physical or chemical changes

Question 8

Which process is used to separate a liquid from a solution based on differences in boiling points?

Accepted Answer

Distillation

Question 9

Which of the following is NOT a physical change?

Accepted Answer

Rusting of iron

Question 10

A compound is formed when sodium reacts with chlorine gas. Which equation correctly represents this reaction?

Accepted Answer

$$ 2\mathrm{Na}(s) + \mathrm{Cl}_2(g) \rightarrow 2\mathrm{NaCl}(s) $$

Question 11

Which of the following is the smallest unit that retains the properties of a molecular compound?

Accepted Answer

Molecule

Question 12

Which property would be most useful for separating a mixture of ethanol and water?

Accepted Answer

Boiling point

Question 13

Which of the following statements about compounds is TRUE?

Accepted Answer

Compounds have unique properties different from the elements they are composed of.

Question 14

A sample of tea with sugar is best classified as:

Accepted Answer

A homogeneous mixture

Question 15

Which of the following is NOT a method for separating mixtures based on physical properties?

Accepted Answer

Electrolysis

Question 16

Which of the following is a chemical property?

Accepted Answer

Reactivity with oxygen

Question 17

Which of the following is a heterogeneous mixture?

Accepted Answer

Wet sand

Question 18

Which statement about the periodic table is correct?

Accepted Answer

Elements are arranged by increasing atomic number.

Question 19

Which of the following is a real-world example of a physical change?

Accepted Answer

Melting ice in a drink

Question 20

Which of the following is a compound?

Accepted Answer

Sodium chloride ($$ \mathrm{NaCl} )$$

Introduction to Chemistry: Matter and Its Classification

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