Q: Which formula correctly calculates the amount of heat ($$q) $$added to a substance?

$$q = \text{mass} \times \text{specific heat capacity} \times \text{temperature change}$$

Q: A sample of water is heated from 20°C to 80°C. If the mass is 100 g and the specific heat capacity is $$4.18 \ \text{J/g} \cdot \text{°C}$$, how much heat is absorbed?

$$q = 100 \times 4.18 \times 60 = 25,080 \ \text{J}$$

Question 1

Which of the following statements best describes a compound?

Accepted Answer

A pure substance composed of two or more elements in fixed, definite proportions.

Question 2

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

Accepted Answer

Oil and water

Question 3

A student mixes sand and salt together in a beaker. Which statement best describes the result?

Accepted Answer

A heterogeneous mixture is formed because the sand and salt remain distinct.

Question 4

Which of the following is a chemical property?

Accepted Answer

Flammability

Question 5

Which statement about energy in chemical reactions is correct?

Accepted Answer

Energy is conserved; it is neither created nor destroyed.

Question 6

A chemical reaction releases energy when TNT explodes. This is an example of:

Accepted Answer

An exothermic reaction

Question 7

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

Accepted Answer

The total mass remains constant during physical and chemical changes.

Question 8

Which formula correctly calculates the amount of heat ($$q) $$added to a substance?

Accepted Answer

$$q = 	ext{mass} 	imes 	ext{specific heat capacity} 	imes 	ext{temperature change}$$

Question 9

Water freezes at 0°C and boils at 100°C. What are these temperatures in Kelvin?

Accepted Answer

Freezes at 273 K, boils at 373 K

Question 10

Which of the following is a physical property?

Accepted Answer

Boiling point

Question 11

A sample of water is heated from 20°C to 80°C. If the mass is 100 g and the specific heat capacity is $$4.18 \ 	ext{J/g} \cdot 	ext{°C}$$, how much heat is absorbed?

Accepted Answer

$$q = 100 	imes 4.18 	imes 60 = 25,080 \ 	ext{J}$$

Question 12

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture with uniform composition throughout, like sweet tea.

Question 13

Which statement is true about elements?

Accepted Answer

Elements cannot be decomposed into simpler substances by chemical transformation.

Question 14

Which of the following is NOT a chemical change?

Accepted Answer

Melting ice

Question 15

Which unit is used to measure energy in the SI system?

Accepted Answer

Joule (J)

Question 16

A system with high potential energy tends to:

Accepted Answer

Change in a way that lowers its potential energy

Question 17

Which of the following is true about physical and chemical changes?

Accepted Answer

Chemical changes result in a new substance with different properties.

Question 18

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

Accepted Answer

Burning gasoline in a car engine

Question 19

Which statement about mixtures is correct?

Accepted Answer

Mixtures have variable composition and can be separated by physical means.

Question 20

Which of the following best describes work in the context of chemistry?

Accepted Answer

The result of a force acting through a distance.

Introduction to Chemistry: Fundamental Concepts and Properties of Matter

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