Q: A student converts $$5.00\ \mathrm{km} to $$meters using dimensional analysis. What is the correct answer?

$$5.00 \times 10^3$\ \mathrm{m}$$

Question 1

Which of the following statements best describes the difference between an exact number and a measured number in chemistry?

Accepted Answer

An exact number is obtained by counting or defined relationships, while a measured number is obtained using a measuring device and has uncertainty.

Question 2

A student measures the mass of a metal cylinder as $$45.67\ \mathrm{g}$$ and its volume as $$12.3\ \mathrm{cm}^3. $$What is the density of the cylinder, reported with the correct number of significant figures?

Accepted Answer

$$3.71\ \mathrm{g/cm}^3$$

Question 3

Which of the following is the correct symbol and meaning for the metric prefix 'nano-'?

Accepted Answer

$$n$$, $$10^{-9}$$

Question 4

A sample contains $$2.50\ \mathrm{mol} of $$glucose ($$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6). $$What is the mass of the sample? (Molar mass of glucose = $$180.16\ \mathrm{g/mol})$$

Accepted Answer

$$450.4\ \mathrm{g}$$

Question 5

Which of the following best describes the difference between an isotope and an ion?

Accepted Answer

An isotope has the same number of protons but a different number of neutrons, while an ion has a different number of electrons than protons.

Question 6

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

Accepted Answer

J.J. Thomson

Question 7

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

$$\mathrm{CH}_2\mathrm{O}$$

Question 8

Which of the following is the correct name for the compound $$\mathrm{FeCl}_3$$?

Accepted Answer

Iron(III) chloride

Question 9

A student needs to prepare $$250.0\ \mathrm{mL} of a$$ $$0.100\ \mathrm{M}$$ NaCl solution. How many grams of NaCl are required? (Molar mass of NaCl = $$58.44\ \mathrm{g/mol})$$

Accepted Answer

$$1.46\ \mathrm{g}$$

Question 10

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties because they have the same number of valence electrons.

Question 11

A sample of magnesium contains $$3.0\ \mathrm{mol} of $$atoms. How many atoms are present in the sample?

Accepted Answer

$$1.8 	imes 10$$^{24}$$ atoms

Question 12

Which of the following is a chemical property?

Accepted Answer

Iron rusts when exposed to oxygen.

Question 13

A student converts $$5.00\ \mathrm{km} to $$meters using dimensional analysis. What is the correct answer?

Accepted Answer

$$5.00 	imes 10^3$\ \mathrm{m}$$

Question 14

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

Accepted Answer

$$\mathrm{F}^-$$

Question 15

A compound has a molar mass of $$58.0\ \mathrm{g/mol}$$ and an empirical formula of $$\mathrm{CH}_2\mathrm{O}. $$What is its molecular formula?

Accepted Answer

$$\mathrm{C}_2\mathrm{H}_4\mathrm{O}_2$$

Question 16

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture in which the composition is not uniform throughout, such as sand in water.

Question 17

A student analyzes a sample of chlorine that contains $$75.77\%$$ $$^{35}\mathrm{Cl} ($$mass = $$34.97\ \mathrm{amu}) $$and $$24.23\%$$ $$^{37}\mathrm{Cl} ($$mass = $$36.97\ \mathrm{amu}). $$What is the average atomic mass of chlorine?

Accepted Answer

$$35.45\ \mathrm{amu}$$

Question 18

Which of the following is the correct formula for aluminum sulfate?

Accepted Answer

$$\mathrm{Al}_2(\mathrm{SO}_4)_3$$

Question 19

A patient receives an intravenous solution containing $$0.90\%$$ NaCl by mass. If the solution has a total mass of $$500.0\ \mathrm{g}$$, how many grams of NaCl are present?

Accepted Answer

$$4.5\ \mathrm{g}$$

Question 20

Which of the following best explains why the mass number of an atom is not found on the periodic table?

Accepted Answer

The periodic table lists the average atomic mass, which accounts for all naturally occurring isotopes, not the mass number of a single isotope.

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

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