Q: A cyclist rides at an average speed of 24 mi/h. If the cyclist wants to bike 195 km, how long (in hours) must they ride? (1 mi = 1.609 km)

$$\frac{195}{24} \times \frac{1}{1.609} = 5.05$$ hours

Q: A 22-g sample of water is heated from $$7^\circ C to$$ $$18^\circ C. $$How much heat is required? ($$c = 4.18\ J/g\cdot ^\circ C)$$

$$22 \times (18-7) \times 4.18 = 1010\ J$$

Q: A hybrid SUV consumes fuel at a rate of $$12.8\ km/L. $$How many miles can the car travel on $$22.5$$ gallons of gasoline? ($$1\ mi = 1.609\ km$$, $$1\ gal = 3.785\ L)$$

$$22.5 \times 3.785 \times 12.8 \div 1.609 = 675$$ miles

Question 1

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

Accepted Answer

A law is a summary of observed behavior, while a theory is an explanation of why the behavior occurs.

Question 2

A chemist decomposes several samples of water and finds that the ratio of the mass of hydrogen to oxygen is always 1:8. Which law does this observation support?

Accepted Answer

Law of Definite Proportions

Question 3

Express the number 0.000000001 s in scientific notation.

Accepted Answer

$$1 	imes 10$$^{-9}$$

Question 4

Which of the following is a chemical property?

Accepted Answer

Flammability of ethanol

Question 5

A cyclist rides at an average speed of 24 mi/h. If the cyclist wants to bike 195 km, how long (in hours) must they ride? (1 mi = 1.609 km)

Accepted Answer

$$\frac{195}{24} 	imes \frac{1}{1.609} = 5.05$$ hours

Question 6

Which of the following mixtures is heterogeneous?

Accepted Answer

Chocolate chip cookie

Question 7

A flask containing 18.32 mL of a liquid weighs 134.2 g with the liquid and 120.4 g when empty. What is the density of the liquid in $$g/mL$$?

Accepted Answer

$$\frac{134.2 - 120.4}{18.32} = 0.753$$ $$g/mL$$

Question 8

Which statement is consistent with Rutherford’s nuclear theory as it was originally stated?

Accepted Answer

The volume of an atom is mostly empty space.

Question 9

A log displaces 2.7 gal of water and weighs 19.8 lb. Is the log oak or pine? (Density of oak = $$0.9\ g/cm^3$, density of pine = 0.4$$\ $$g/cm^3$$, 1 gal = 3.785 L, 1 L = 1000 cm³, 1 lb = 453.6 g)

Accepted Answer

Oak, because its density is closer to $$0.9\ g/cm^3$

Question 10

Which of the following statements about electrons is false?

Accepted Answer

Most atoms have more electrons than protons.

Question 11

A 22-g sample of water is heated from $$7^\circ C to$$ $$18^\circ C. $$How much heat is required? ($$c = 4.18\ J/g\cdot ^\circ C)$$

Accepted Answer

$$22 	imes (18-7) 	imes 4.18 = 1010\ J$$

Question 12

Which of the following is a physical property of ozone?

Accepted Answer

Gas at room temperature

Question 13

A sample contains 1.5 g of hydrogen and 12 g of oxygen. What is the simplest statement that summarizes this observation?

Accepted Answer

Water contains hydrogen and oxygen in a mass ratio of 1:8.

Question 14

Which of the following is a homogeneous mixture?

Accepted Answer

Baby oil

Question 15

Which process is endothermic?

Accepted Answer

Dry ice subliming

Question 16

A hybrid SUV consumes fuel at a rate of $$12.8\ km/L. $$How many miles can the car travel on $$22.5$$ gallons of gasoline? ($$1\ mi = 1.609\ km$$, $$1\ gal = 3.785\ L)$$

Accepted Answer

$$22.5 	imes 3.785 	imes 12.8 \div 1.609 = 675$$ miles

Question 17

Which of the following is a pure substance?

Accepted Answer

Pure water

Question 18

Which of the following statements is an observation?

Accepted Answer

A stone dropped from an altitude of 450 m falls to the ground in 9.6 s.

Introduction to Chemistry Review: Concepts, Calculations, and Scientific Reasoning

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