Q: A rectangular solid has dimensions 2.50 cm × 3.00 cm × 4.00 cm. What is its volume, reported to the correct number of significant figures?

$$V = 2.50 \times 3.00 \times 4.00 = 30.0 cm$^3$$

Q: A student calculates the percent error for a measurement. Which formula should they use?

$$\text{Percent error} = \frac{\text{measured value} - \text{accepted value}}{\text{accepted value}} \times 100$$

Q: A sample of water is heated from 20.0°C to 80.0°C. If the mass of water is 100.0 g and the specific heat capacity is $$4.184 J/g$$°C, how much heat is absorbed?

$$q = m \times c \times \Delta T = 100.0 \times 4.184 \times (80.0 - 20.0) = 25,104 J$$

Q: A student wants to convert 79 cm into meters using dimensional analysis. Which conversion factor should they use?

$$1 \text{ m} = 100 \text{ cm}$$

Q: A student measures the density of a metal sample as 7.85 g/cm$$^3. $$The accepted value is 7.90 g/cm$$^3. $$What is the percent error?

$$\frac{7.85 - 7.90}{7.90} \times 100 = -0.63\%$$

Question 1

Which of the following best describes the difference between mass and weight?

Accepted Answer

Mass is the measure of the amount of matter in an object, while weight is the measure of the pulling force of gravity on an object.

Question 2

A student measures the temperature of a sample and records 25.6°C. What is this temperature in Kelvin?

Accepted Answer

$$K = ^\circ C + 273.15 = 25.6 + 273.15 = 298.75 K$$

Question 3

Which statement about significant figures is correct?

Accepted Answer

All nonzero digits are always significant.

Question 4

A rectangular solid has dimensions 2.50 cm × 3.00 cm × 4.00 cm. What is its volume, reported to the correct number of significant figures?

Accepted Answer

$$V = 2.50 	imes 3.00 	imes 4.00 = 30.0 cm$^3$$

Question 5

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

Accepted Answer

Sand and water

Question 6

A student calculates the percent error for a measurement. Which formula should they use?

Accepted Answer

$$	ext{Percent error} = \frac{	ext{measured value} - 	ext{accepted value}}{	ext{accepted value}} 	imes 100$$

Question 7

Which process is endothermic?

Accepted Answer

Melting ice

Question 8

A sample of water is heated from 20.0°C to 80.0°C. If the mass of water is 100.0 g and the specific heat capacity is $$4.184 J/g$$°C, how much heat is absorbed?

Accepted Answer

$$q = m 	imes c 	imes \Delta T = 100.0 	imes 4.184 	imes (80.0 - 20.0) = 25,104 J$$

Question 9

Which of the following is NOT considered matter?

Accepted Answer

Light

Question 10

Which statement best describes the Law of Conservation of Mass?

Accepted Answer

Mass is neither created nor destroyed in a chemical reaction.

Question 11

A measurement is recorded as 0.00340 g. How many significant figures does this value have?

Accepted Answer

3

Question 12

Which of the following is a physical change?

Accepted Answer

Boiling water

Question 13

A student wants to convert 79 cm into meters using dimensional analysis. Which conversion factor should they use?

Accepted Answer

$$1 	ext{ m} = 100 	ext{ cm}$$

Question 14

Which of the following is the correct scientific notation for 0.0003405?

Accepted Answer

$$3.405 	imes 10$$^{-4}$$

Question 15

Which of the following is a compound?

Accepted Answer

Water ($$H_2O)$$

Question 16

A student adds 23.538 cm and 25.68 cm. What is the sum, reported to the correct number of decimal places?

Accepted Answer

49.22 cm

Question 17

Which of the following is a manipulated variable in an experiment?

Accepted Answer

The variable you plan to change during the experiment

Question 18

A student measures the density of a metal sample as 7.85 g/cm$$^3. $$The accepted value is 7.90 g/cm$$^3. $$What is the percent error?

Accepted Answer

$$\frac{7.85 - 7.90}{7.90} 	imes 100 = -0.63\%$$

Question 19

Which of the following statements about scientific theories and laws is correct?

Accepted Answer

A scientific law summarizes past observations and predicts future ones, while a theory provides a broader explanation and can predict behavior.

Introduction to Chemistry: Scientific Method, Measurement, and Problem Solving

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