$1.81 \times 10^{24}$ formula units

$\text{Density} = \frac{\text{mass}}{\text{volume}}$

Question 1

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture where the components are not evenly distributed, such as oil and water.

Question 2

Which of the following is the correct conversion factor to change 5.00 cm to inches? (Use $1 	ext{ in} = 2.54 	ext{ cm}$)

Accepted Answer

$5.00 	ext{ cm} 	imes \frac{1 	ext{ in}}{2.54 	ext{ cm}}$

Question 3

Which statement about Dalton’s atomic theory is correct?

Accepted Answer

All atoms of a given element are identical in mass and properties.

Question 4

A student measures the mass of a sample as 2.50 g, 2.48 g, and 2.51 g. The true mass is 2.80 g. Which statement best describes the measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 5

Which of the following is a physical change?

Accepted Answer

Melting of ice to form liquid water.

Question 6

Which scientist is credited with discovering the electron using the cathode ray tube experiment?

Accepted Answer

J.J. Thomson

Question 7

What is the correct number of significant figures in the measurement 0.00450 m?

Accepted Answer

3

Question 8

Which of the following best describes a compound?

Accepted Answer

A substance made up of two or more elements chemically bonded together.

Question 9

Which of the following is the correct scientific notation for 0.000123?

Accepted Answer

$1.23 	imes 10^{-4}$

Question 10

A sample contains 3.0 moles of NaCl. How many formula units of NaCl are present? (Use $1 	ext{ mol} = 6.022 	imes 10^{23}$ particles)

Accepted Answer

$1.81 	imes 10^{24}$ formula units

Question 11

Which of the following is NOT a base SI unit?

Accepted Answer

Gram

Question 12

Which of the following statements about the law of conservation of mass is correct?

Accepted Answer

Mass is neither created nor destroyed in a chemical reaction.

Question 13

Which of the following is the correct formula for density?

Accepted Answer

$	ext{Density} = \frac{	ext{mass}}{	ext{volume}}$

Question 14

A student needs to convert 250.0 mL to liters. What is the correct answer? (Use $1 	ext{ L} = 1000 	ext{ mL}$)

Accepted Answer

$0.250$ L

Question 15

Which of the following is a chemical property?

Accepted Answer

Ability to react with acid

Question 16

Which scientist’s gold foil experiment led to the discovery of the atomic nucleus?

Accepted Answer

Ernest Rutherford

Question 17

Which of the following is the correct value for Avogadro’s number?

Accepted Answer

$6.022 	imes 10^{23}$

Question 18

A student mixes two clear solutions and observes the formation of a white precipitate. What type of change has occurred?

Accepted Answer

Chemical change

Question 19

Which of the following is the correct conversion for 5.00 kg to grams? (Use $1 	ext{ kg} = 1000 	ext{ g}$)

Accepted Answer

$5.00 	imes 10^{3}$ g

Question 20

Which of the following best describes a law in science?

Accepted Answer

A statement based on repeated experimental observations that describes some aspect of the world.

Chem 141 Exam 1 Study Checklist and Key Concepts

Study Guide - Practice Questions