Q: A student needs to convert $$5.00\ \mathrm{km} to $$centimeters. Which of the following is the correct answer and conversion setup?

$$5.00\ \mathrm{km} \times \frac{10^3$\ \mathrm{m}}{1\ \mathrm{km}} \times \frac{100\ \mathrm{cm}}{1\ \mathrm{m}} = 5.00 \times 10^5$\ \mathrm{cm}$$

Question 1

A sample of an unknown metal has a mass of 45.6 g and a volume of 16.0 mL. What is the density of the metal, and which of the following is the correct calculation using significant figures?

Accepted Answer

$$\frac{45.6\ \mathrm{g}}{16.0\ \mathrm{mL}} = 2.85\ \mathrm{g/mL}$$

Question 2

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 3

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

Accepted Answer

$$\mathrm{CH_2O}$$

Question 4

Which of the following is a derived SI unit?

Accepted Answer

$$\mathrm{m^3$} ($$cubic meter)

Question 5

A student measures the mass of a beaker as 125.40 g and the mass of the beaker plus a sample as 130.2 g. What is the correct mass of the sample, reported with the correct number of significant figures?

Accepted Answer

$$4.8\ \mathrm{g}$$

Question 6

Which scientist is credited with discovering the electron and how?

Accepted Answer

J.J. Thomson, using the cathode ray tube experiment.

Question 7

A sample of sodium chloride ($$\mathrm{NaCl}) $$contains $$2.00\ \mathrm{mol} of $$sodium ions. How many formula units of $$\mathrm{NaCl}$$ are present in the sample?

Accepted Answer

$$1.20 	imes 10$$^{24}$$

Question 8

Which of the following best describes the difference between an ionic and a covalent compound?

Accepted Answer

Ionic compounds are formed from the transfer of electrons between metals and nonmetals, while covalent compounds are formed from the sharing of electrons between nonmetals.

Question 9

A patient receives an intravenous solution containing $$0.90\ \mathrm{g} of $$sodium chloride ($$\mathrm{NaCl}) $$per $$100\ \mathrm{mL} of $$solution. What is the percent by mass of $$\mathrm{NaCl} in $$the solution?

Accepted Answer

$$0.90\%$$

Question 10

Which of the following is the correct name for $$\mathrm{Fe_2O_3}$$?

Accepted Answer

Iron(III) oxide

Question 11

A sample of magnesium contains $$1.20 	imes 10$$^{24}$$ atoms. What is the mass of this sample? (Molar mass of Mg = 24.31$$\ \mathrm{g/mol}$$)

Accepted Answer

$$48.6\ \mathrm{g}$$

Question 12

Which of the following is an exact number?

Accepted Answer

There are 12 eggs in a dozen.

Question 13

Which of the following elements is a noble gas?

Accepted Answer

Neon ($$\mathrm{Ne})$$

Question 14

A student needs to convert $$5.00\ \mathrm{km} to $$centimeters. Which of the following is the correct answer and conversion setup?

Accepted Answer

$$5.00\ \mathrm{km} 	imes \frac{10^3$\ \mathrm{m}}{1\ \mathrm{km}} 	imes \frac{100\ \mathrm{cm}}{1\ \mathrm{m}} = 5.00 	imes 10^5$\ \mathrm{cm}$$

Question 15

Which of the following best describes the group and period location of halogens on the periodic table?

Accepted Answer

Group 17 (7A), various periods

Question 16

A sample of glucose ($$\mathrm{C_6H_{12}O_6$}) $$has a mass of $$18.0\ \mathrm{g}. $$How many moles of glucose are present? (Molar mass of glucose = $$180.0\ \mathrm{g/mol})$$

Accepted Answer

$$0.100\ \mathrm{mol}$$

Question 17

Which of the following is the correct percent composition by mass of oxygen in water ($$\mathrm{H_2O}$$)? (Molar mass: H = $$1.01\ \mathrm{g/mol}$$, O = $$16.00\ \mathrm{g/mol})$$

Accepted Answer

$$88.8\%$$

Question 18

Which of the following ions is isoelectronic with neon ($$\mathrm{Ne}$$)?

Accepted Answer

$$\mathrm{F^-}$$

Question 19

A student is asked to name the compound $$\mathrm{K_2SO_4}. $$Which of the following is the correct name?

Accepted Answer

Potassium sulfate

Question 20

Which of the following best describes the process of dimensional analysis?

Accepted Answer

A method of converting between units using conversion factors.

CHEM 141 Exam 1 Study Guide: Matter, Atoms, and Molecules

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