$$225 \times 1000 \times 4.184 = 941,400\ \mathrm{J}$$

Question 1

Which of the following statements best describes a compound?

Accepted Answer

A pure substance composed of two or more elements that are chemically bonded in fixed definite proportions.

Question 2

Which of the following is a chemical property?

Accepted Answer

Flammability

Question 3

A student mixes sand and water in a beaker. What type of mixture is formed?

Accepted Answer

Heterogeneous mixture

Question 4

Which process is used to separate a mixture of ethanol and water based on their different boiling points?

Accepted Answer

Distillation

Question 5

Which of the following best describes the law of conservation of mass?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 6

What is the density of a substance with a mass of 50 g and a volume of 10 cm$$^3$$?

Accepted Answer

$$d = \frac{50}{10} = 5\ \mathrm{g/cm^3$}$$

Question 7

Which of the following is an example of a physical change?

Accepted Answer

Ice melting

Question 8

Which statement about elements is correct?

Accepted Answer

Elements are pure substances that cannot be broken down into simpler substances.

Question 9

A solution of sodium chloride in water is best classified as:

Accepted Answer

A homogeneous mixture

Question 10

Which of the following is true about gases?

Accepted Answer

Gases are compressible and have variable volume and shape.

Question 11

Which of the following is NOT a type of intermolecular force?

Accepted Answer

Ionic bond

Question 12

Which of the following is an example of a crystalline solid?

Accepted Answer

Sodium chloride (NaCl)

Question 13

Which equation correctly represents the conversion from Celsius to Kelvin?

Accepted Answer

$$K = \mathrm{C} + 273$$

Question 14

Which of the following best describes an exothermic reaction?

Accepted Answer

A reaction that releases energy to the surroundings.

Question 15

A chocolate candy contains 225 Cal of nutritional energy. How many joules (J) does it contain?

Accepted Answer

$$225 	imes 1000 	imes 4.184 = 941,400\ \mathrm{J}$$

Question 16

Which of the following is a correct statement about physical and chemical changes?

Accepted Answer

Physical changes alter the appearance but not the composition of matter.

Question 17

Which of the following is a correct balanced chemical equation for the complete combustion of ethanol ($$C_2H_5OH$$)?

Accepted Answer

$$C_2H_5OH + 3O_2 \rightarrow 2CO_2 + 3H_2O$$

Question 18

Which of the following is NOT a physical property?

Accepted Answer

Reactivity with oxygen

Question 19

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture with the same composition throughout

Question 20

Which of the following is a correct statement about energy in chemical reactions?

Accepted Answer

Energy can be transferred or transformed but is conserved.

Matters, Compounds, and Their Properties: Foundations of General Chemistry

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