Q: A sample contains 3.00 moles of sodium atoms. How many atoms are present in the sample?

$$3.00 \times 6.022 \times 10$$^{23}$$ = 1.81 \times 10$$^{24}$$\ \text{atoms}$$

Q: A naturally occurring element has two isotopes: 69.17% with mass 62.930 amu and 30.83% with mass 64.928 amu. What is the average atomic mass?

$$(0.6917 \times 62.930) + (0.3083 \times 64.928) = 63.55\ \mathrm{amu}$$

Q: Which of the following is a correct conversion setup to convert 5.00 feet to millimeters? (1 ft = 12 in, 1 in = 2.54 cm, 1 cm = 10 mm)

$$5.00\ \mathrm{ft} \times \frac{12\ \mathrm{in}}{1\ \mathrm{ft}} \times \frac{2.54\ \mathrm{cm}}{1\ \mathrm{in}} \times \frac{10\ \mathrm{mm}}{1\ \mathrm{cm}}$$

Q: What is the molar mass of calcium hydroxide, $$\mathrm{Ca(OH)_2}$$? (Atomic masses: Ca = 40.08, O = 16.00, H = 1.01)

$$40.08 + 2 \times (16.00 + 1.01) = 74.10\ \mathrm{g/mol}$$

Question 1

Which of the following measurements contains the correct number of significant figures?

Accepted Answer

0.04050 has 4 significant figures

Question 2

A student measures the mass of a metal sample as 12.34 g and its volume as 4.2 mL. What is the density of the metal, reported with the correct number of significant figures?

Accepted Answer

$$\frac{12.34\ \mathrm{g}}{4.2\ \mathrm{mL}} = 2.9\ \mathrm{g/mL}$$

Question 3

Which of the following is the correct SI base unit for temperature?

Accepted Answer

Kelvin (K)

Question 4

Convert 25.0 °C to Kelvin. Use the correct formula and significant figures.

Accepted Answer

$$25.0 + 273.15 = 298.2\ \mathrm{K}$$

Question 5

A sample contains 3.00 moles of sodium atoms. How many atoms are present in the sample?

Accepted Answer

$$3.00 	imes 6.022 	imes 10$$^{23}$$ = 1.81 	imes 10$$^{24}$$\ 	ext{atoms}$$

Question 6

Which of the following is the correct name for the compound Ca(OH)$$_2$$?

Accepted Answer

Calcium hydroxide

Question 7

Which of the following formulas represents ammonium nitrate?

Accepted Answer

$$\mathrm{NH_4NO_3}$$

Question 8

A naturally occurring element has two isotopes: 69.17% with mass 62.930 amu and 30.83% with mass 64.928 amu. What is the average atomic mass?

Accepted Answer

$$(0.6917 	imes 62.930) + (0.3083 	imes 64.928) = 63.55\ \mathrm{amu}$$

Question 9

Which of the following is a correct conversion setup to convert 5.00 feet to millimeters? (1 ft = 12 in, 1 in = 2.54 cm, 1 cm = 10 mm)

Accepted Answer

$$5.00\ \mathrm{ft} 	imes \frac{12\ \mathrm{in}}{1\ \mathrm{ft}} 	imes \frac{2.54\ \mathrm{cm}}{1\ \mathrm{in}} 	imes \frac{10\ \mathrm{mm}}{1\ \mathrm{cm}}$$

Question 10

Which of the following is the correct formula for iron(III) sulfate?

Accepted Answer

$$\mathrm{Fe_2$(SO_4$)_3}$$

Question 11

How many moles are in 18.0 grams of water ($$\mathrm{H_2O}$$)? (Molar mass of $$\mathrm{H_2O} = 18.0 g/$$mol)

Accepted Answer

$$\frac{18.0\ \mathrm{g}}{18.0\ \mathrm{g/mol}} = 1.00\ \mathrm{mol}$$

Question 12

Which of the following is the correct name for the compound $$\mathrm{N_2O_5}$$?

Accepted Answer

Dinitrogen pentoxide

Question 13

A neutral atom of phosphorus has an atomic number of 15 and a mass number of 31. How many neutrons does it have?

Accepted Answer

$$31 - 15 = 16$$ neutrons

Question 14

Which of the following ions is a cation?

Accepted Answer

$$\mathrm{Na^+}$$

Question 15

What is the molar mass of calcium hydroxide, $$\mathrm{Ca(OH)_2}$$? (Atomic masses: Ca = 40.08, O = 16.00, H = 1.01)

Accepted Answer

$$40.08 + 2 	imes (16.00 + 1.01) = 74.10\ \mathrm{g/mol}$$

Question 16

Which of the following is the correct name for the binary acid $$\mathrm{HBr}$$?

Accepted Answer

Hydrobromic acid

Question 17

A sample of gas has a mass of 2.50 g and occupies a volume of 1.20 L. What is its density in $$\mathrm{g/L}$$, reported with the correct number of significant figures?

Accepted Answer

$$\frac{2.50\ \mathrm{g}}{1.20\ \mathrm{L}} = 2.1\ \mathrm{g/L}$$

Question 18

Which of the following is the correct formula for sodium hydrogen carbonate?

Accepted Answer

$$\mathrm{$$NaHCO_3$$}$$

Question 19

Which of the following is the correct name for $$\mathrm{$$FeCl_2$$}$$?

Accepted Answer

Iron(II) chloride

Exam 1 Study Guide: Chapters 1–3 (Matter, Measurement, Atoms, Molecules, and Nomenclature)

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