Q: Convert 125 mg to kilograms using the correct number of significant figures.

$125\ \mathrm{mg} \times \frac{1\ \mathrm{g}}{1000\ \mathrm{mg}} \times \frac{1\ \mathrm{kg}}{1000\ \mathrm{g}} = 1.25 \times 10^{-5}\ \mathrm{kg}$

Q: A student needs to convert 2.5 km to meters. Which of the following is the correct conversion?

$2.5\ \mathrm{km} \times \frac{1000\ \mathrm{m}}{1\ \mathrm{km}} = 2500\ \mathrm{m}$

Question 1

Which of the following best describes a scientific theory?

Accepted Answer

An explanation that fits all available data and has not yet been disproven.

Question 2

Which of the following is an example of an intensive property?

Accepted Answer

Density

Question 3

A student measures the mass of a metal sample as 13.5 g and its volume as 10.0 mL. What is the density of the metal?

Accepted Answer

$d = \frac{13.5\ \mathrm{g}}{10.0\ \mathrm{mL}} = 1.35\ \mathrm{g/mL}$

Question 4

Which of the following changes is a chemical change?

Accepted Answer

Burning of gasoline

Question 5

A sample of water is heated from 25°C to 100°C. What type of change is this?

Accepted Answer

Physical change

Question 6

Which of the following statements about correlation and causation is correct?

Accepted Answer

Correlation does not imply causation.

Question 7

Convert 125 mg to kilograms using the correct number of significant figures.

Accepted Answer

$125\ \mathrm{mg} 	imes \frac{1\ \mathrm{g}}{1000\ \mathrm{mg}} 	imes \frac{1\ \mathrm{kg}}{1000\ \mathrm{g}} = 1.25 	imes 10^{-5}\ \mathrm{kg}$

Question 8

Which of the following is a pure substance?

Accepted Answer

Aluminum foil

Question 9

A student records the following measurements for the mass of a sample: 2.51 g, 2.50 g, 2.52 g. The true mass is 2.00 g. Which statement best describes the measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 10

Which of the following is the correct formula for converting Celsius to Kelvin?

Accepted Answer

$K = ^\circ C + 273.15$

Question 11

A mixture of sand and salt can be separated by which method?

Accepted Answer

Filtration

Question 12

Which of the following numbers has 3 significant figures?

Accepted Answer

0.0110

Question 13

Which of the following is an extensive property?

Accepted Answer

Mass

Question 14

A student adds 12.02 g, 542.21 g, and 2.00347 g. What is the sum, rounded to the correct number of decimal places?

Accepted Answer

$556.2\ \mathrm{g}$

Question 15

Which of the following best describes a molecule?

Accepted Answer

A combination of two or more atoms bonded together.

Question 16

A student needs to convert 2.5 km to meters. Which of the following is the correct conversion?

Accepted Answer

$2.5\ \mathrm{km} 	imes \frac{1000\ \mathrm{m}}{1\ \mathrm{km}} = 2500\ \mathrm{m}$

Question 17

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

Accepted Answer

A hypothesis is a proposed explanation that can be tested, while a theory is a comprehensive explanation supported by evidence.

Question 18

A student measures the length of a rod as 12.50 cm, 12.51 cm, and 12.49 cm. The true length is 12.50 cm. Which statement is correct?

Accepted Answer

The measurements are both accurate and precise.

Question 19

Which of the following is a heterogeneous mixture?

Accepted Answer

Salad with lettuce and tomatoes

Question 20

A metal has a density of $2.70\ \mathrm{g/cm^3}$ and a volume of $25.0\ \mathrm{cm^3}$. What is its mass?

Accepted Answer

$m = 2.70\ \mathrm{g/cm^3} 	imes 25.0\ \mathrm{cm^3} = 67.5\ \mathrm{g}$

Chapter 1: Measurement and the Scientific Problem – Foundations of Chemistry

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