Q: A sample of a compound contains 12.0 g of carbon and 32.0 g of oxygen. What is the mass percent of carbon in the compound? Use the formula $$\text{mass percent} = \frac{\text{mass of element}}{\text{total mass}} \times 100\%.$$

$$\frac{12.0}{44.0} \times 100\% = 27.3\%$$

Q: A sample of neon gas has a mass of 10.0 g. How many atoms of neon are present? (Molar mass of Ne = 20.18 g/mol, $$1\ \text{mol} = 6.022 \times 10$$^{23}$$ atoms)

$$2.98 \times 10$$^{23}$$ atoms

Question 1

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

Accepted Answer

Iron rusting when exposed to air

Question 2

A sample of a compound contains 12.0 g of carbon and 32.0 g of oxygen. What is the mass percent of carbon in the compound? Use the formula $$	ext{mass percent} = \frac{	ext{mass of element}}{	ext{total mass}} 	imes 100\%.$$

Accepted Answer

$$\frac{12.0}{44.0} 	imes 100\% = 27.3\%$$

Question 3

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 4

A student measures the mass of a metal cylinder as 12.34 g and its volume as 4.56 mL. What is the density of the cylinder, reported to the correct number of significant figures? Use $$d = \frac{m}{V}.$$

Accepted Answer

$$2.71\ 	ext{g/mL}$$

Question 5

Which of the following best describes an intensive property?

Accepted Answer

A property that does not depend on the amount of substance present

Question 6

Which of the following correctly gives the number of protons, neutrons, and electrons in $$^{35}_{17}	ext{Cl}^-$$?

Accepted Answer

17 protons, 18 neutrons, 18 electrons

Question 7

Which of the following compounds is an ionic compound?

Accepted Answer

$$	ext{NaCl}$$

Question 8

A sample contains $$3.01 	imes 10$$^{23}$$ molecules of water. How many moles of water does this represent? Use 1$$\ 	ext{mol} = 6.022 	imes $$10^{23}$$ molecules.

Accepted Answer

$$0.500\ 	ext{mol}$$

Question 9

Which of the following elements is a metalloid?

Accepted Answer

Silicon ($$	ext{Si})$$

Question 10

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

Accepted Answer

$$	ext{CH}_2	ext{O}$$

Question 11

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

Accepted Answer

Iron(III) oxide

Question 12

A 250.0 mL sample of seawater has a mass of 257.5 g. What is the density of the seawater? Use $$d = \frac{m}{V}.$$

Accepted Answer

$$1.03\ 	ext{g/mL}$$

Question 13

Which of the following is the correct formula for magnesium nitrate?

Accepted Answer

$$	ext{Mg(NO}_3)_2$$

Question 14

A sample of neon gas has a mass of 10.0 g. How many atoms of neon are present? (Molar mass of Ne = 20.18 g/mol, $$1\ 	ext{mol} = 6.022 	imes 10$$^{23}$$ atoms)

Accepted Answer

$$2.98 	imes 10$$^{23}$$ atoms

Question 15

Which of the following best describes the difference between a pure substance and a mixture?

Accepted Answer

A pure substance has a fixed composition; a mixture has variable composition.

Question 16

Convert 25.0 $$^\circC to $$Kelvin. Use $$K = ^\circ	ext{C} + 273.15.$$

Accepted Answer

$$298.15\ 	ext{K}$$

Question 17

Which of the following is the correct molar mass for calcium phosphate, $$	ext{Ca}_3(	ext{PO}_4)_2$$? (Ca: 40.08 g/mol, P: 30.97 g/mol, O: 16.00 g/mol)

Accepted Answer

$$310.18\ 	ext{g/mol}$$

Question 18

Which of the following best describes the group and period location of bromine ($$	ext{Br}) on $$the periodic table?

Accepted Answer

Group 17, Period 4

Question 19

A compound is found to contain 58.8% barium, 13.7% sulfur, and 27.5% oxygen by mass. What is its empirical formula? (Ba: 137.33 g/mol, S: 32.07 g/mol, O: 16.00 g/mol)

Accepted Answer

$$	ext{BaSO}_4$$

Question 20

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

Accepted Answer

Dinitrogen pentoxide

CHEM 101 Study Guide: Chapters 1-3 – Matter, Atoms, Molecules, and Compounds

Study Guide - Practice Questions

Study Guide - Flashcards