Question 1

Which of the following statements best describes the difference between atomic number and mass number for an atom?

Accepted Answer

The atomic number is the number of protons, while the mass number is the sum of protons and neutrons.

Question 2

A sample contains 2.00 moles of sodium chloride ($$\mathrm{NaCl}). $$What is the mass of this sample? ($$\mathrm{Na} = 22.99\ \mathrm{g/mol}$$, $$\mathrm{Cl} = 35.45\ \mathrm{g/mol})$$

Accepted Answer

$$116.88\ \mathrm{g}$$

Question 3

Which of the following ions is a polyatomic ion?

Accepted Answer

$$\mathrm{SO}_4$$^{2-}$$

Question 4

Which of the following compounds is an example of a molecular compound?

Accepted Answer

$$\mathrm{CO}_2$$

Question 5

Calculate the percent composition by mass of oxygen in $$\mathrm{H}_2\mathrm{O}.$$

Accepted Answer

$$88.8\%$$

Question 6

Which of the following best describes an empirical formula?

Accepted Answer

It shows the simplest whole-number ratio of atoms in a compound.

Question 7

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

Accepted Answer

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

Question 8

Which of the following is the correct name for $$\mathrm{Fe}_2\mathrm{O}_3$$?

Accepted Answer

Iron(III) oxide

Question 9

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 10

A patient receives a dose of 0.250 mol of glucose ($$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6) $$intravenously. What is the mass of glucose administered? ($$\mathrm{C} = 12.01\ \mathrm{g/mol}$$, $$\mathrm{H} = 1.008\ \mathrm{g/mol}$$, $$\mathrm{O} = 16.00\ \mathrm{g/mol})$$

Accepted Answer

$$45.05\ \mathrm{g}$$

Question 11

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

Accepted Answer

$$\mathrm{(NH}_4)_2\mathrm{SO}_4$$

Question 12

Which of the following best describes the difference between ionic and covalent bonding?

Accepted Answer

Ionic bonding involves the transfer of electrons, while covalent bonding involves the sharing of electrons.

Question 13

What is the name of $$\mathrm{H}_2\mathrm{SO}_4$$?

Accepted Answer

Sulfuric acid

Question 14

A sample of magnesium contains $$1.20 	imes 10$$^{24}$$ atoms. How many moles of magnesium are present? (N_A = 6.022$$ 	imes $$10^{23}$$\ \mathrm{mol}^{-1}$$)

Accepted Answer

$$0.500\ \mathrm{mol}$$

Question 15

Which of the following is the correct name for $$\mathrm{N}_2\mathrm{O}_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 16

Which of the following is an example of an oxyanion?

Accepted Answer

$$\mathrm{NO}_3^-$$

Question 17

A compound is found to have a molar mass of $$58.0\ \mathrm{g/mol}$$ and an empirical formula of $$\mathrm{C}_2\mathrm{H}_5. $$What is its molecular formula?

Accepted Answer

$$\mathrm{C}_4\mathrm{H}_{10}$$

Question 18

Which of the following is the correct formula for calcium phosphate?

Accepted Answer

$$\mathrm{Ca}_3(\mathrm{PO}_4)_2$$

Question 19

Which of the following best describes a monatomic ion?

Accepted Answer

An ion composed of a single atom

Question 20

A 5.00 g sample of a compound contains 2.00 g of carbon, 0.33 g of hydrogen, and 2.67 g of oxygen. What is the empirical formula of the compound?

Accepted Answer

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

Study Guide: Atomic Structure, Moles, and Chemical Nomenclature

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