Q: A sample contains 2.50 moles of sodium chloride (NaCl). How many formula units of NaCl are present in the sample? Use $$N_A = 6.022 \times 10$$^{23}$$ mol$$^{-1}$$.

$$1.51 \times 10$$^{24}$$ formula units

Q: Which of the following is the correct conversion factor to change inches to centimeters?

$$1 \text{ in} = 2.54 \text{ cm}$$

Q: Which of the following is the correct formula for calculating percent composition by mass of an element in a compound?

$$\% \text{ composition} = \frac{\text{mass of element}}{\text{total mass of compound}} \times 100$$

Q: Which of the following is the correct formula for calculating the molar mass of a compound?

$$\text{Molar mass} = \sum (\text{number of atoms of each element} \times \text{atomic mass of element})$$

Question 1

Which of the following best describes an isotope?

Accepted Answer

An atom with the same number of protons but a different number of neutrons.

Question 2

A sample contains 2.50 moles of sodium chloride (NaCl). How many formula units of NaCl are present in the sample? Use $$N_A = 6.022 	imes 10$$^{23}$$ mol$$^{-1}$$.

Accepted Answer

$$1.51 	imes 10$$^{24}$$ formula units

Question 3

Which of the following is the correct formula for calculating the density ($$d) of a $$substance?

Accepted Answer

$$d = \frac{m}{V}$$

Question 4

Which statement about compounds is correct?

Accepted Answer

Compounds are substances composed of two or more elements chemically combined in fixed proportions.

Question 5

A student converts 3.00 gallons of water to liters. What is the correct volume in liters? (Use $$1 	ext{ gal} = 3.785 	ext{ L})$$

Accepted Answer

$$11.4 	ext{ L}$$

Question 6

Which of the following is NOT a correct example of a physical property?

Accepted Answer

Ability to rust

Question 7

Which of the following is the correct formula for calculating the number of moles ($$n) $$from mass ($$m) $$and molar mass ($$M$$)?

Accepted Answer

$$n = \frac{m}{M}$$

Question 8

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture in which the composition is not uniform throughout.

Question 9

A chemist needs to prepare 250.0 g of a solution with a density of $$1.20 	ext{ g/mL}. $$What is the volume of the solution in mL?

Accepted Answer

$$208 	ext{ mL}$$

Question 10

Which of the following is the correct conversion factor to change inches to centimeters?

Accepted Answer

$$1 	ext{ in} = 2.54 	ext{ cm}$$

Question 11

Which of the following is the correct formula for calculating percent composition by mass of an element in a compound?

Accepted Answer

$$\% 	ext{ composition} = \frac{	ext{mass of element}}{	ext{total mass of compound}} 	imes 100$$

Question 12

Which of the following is a correct example of a chemical change?

Accepted Answer

Burning of gasoline in a car engine

Question 13

A student measures the mass of a sample as 5.00 lb. What is the mass in grams? (Use $$1 	ext{ lb} = 453.6 	ext{ g})$$

Accepted Answer

$$2268 	ext{ g}$$

Question 14

Which of the following is the correct formula for calculating the molar mass of a compound?

Accepted Answer

$$	ext{Molar mass} = \sum (	ext{number of atoms of each element} 	imes 	ext{atomic mass of element})$$

Question 15

Which of the following is the correct chemical symbol for potassium?

Accepted Answer

K

Question 16

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

CH$$_2O$$

Question 17

Which of the following is the correct definition of atomic number?

Accepted Answer

The number of protons in the nucleus of an atom.

Question 18

A student needs to convert 5.00 km to miles. What is the correct value? (Use $$1 	ext{ mi} = 1.6093 	ext{ km})$$

Accepted Answer

$$3.11 	ext{ mi}$$

Question 19

Which of the following is the correct formula for calculating the number of particles ($$N) in a $$sample given the number of moles ($$n) $$and Avogadro's number ($$N_A$$)?

Accepted Answer

$$N = n 	imes N_A$$

General Chemistry I: Syllabus and Core Concepts Study Guide

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