Q: How many atoms are present in $$2.00\ \mathrm{mol} of $$oxygen gas ($$\mathrm{O}_2$$)?

$$2.41 \times 10$$^{24}$$ atoms

Q: Which of the following statements about Avogadro’s number is correct?

Avogadro’s number is $$6.022 \times 10$$^{23}$$ and represents the number of particles in one mole.

Question 1

A laboratory thermometer reads 25.0 $$^\circC. $$What is the temperature in Kelvin?

Accepted Answer

$$298.2\ \mathrm{K}$$

Question 2

A student measures the mass of a metal block as $$45.67\ \mathrm{g}$$ and its volume as $$16.2\ \mathrm{cm}^3. $$What is the density of the metal?

Accepted Answer

$$2.82\ \mathrm{g/cm}^3$$

Question 3

Which of the following statements best describes the difference between precision and accuracy?

Accepted Answer

Precision refers to how close measurements are to each other, while accuracy refers to how close measurements are to the true value.

Question 4

Which of the following is an isotope of $$^{12}\mathrm{C}$$?

Accepted Answer

$$^{14}\mathrm{C}$$

Question 5

Which of the following ions is a cation?

Accepted Answer

$$\mathrm{Na}^+$$

Question 6

Which group on the periodic table contains elements that are all metals?

Accepted Answer

Group 1 (alkali metals)

Question 7

How many atoms are present in $$2.00\ \mathrm{mol} of $$oxygen gas ($$\mathrm{O}_2$$)?

Accepted Answer

$$2.41 	imes 10$$^{24}$$ atoms

Question 8

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

Accepted Answer

A mixture can be separated by physical means, while a compound can only be separated by chemical means.

Question 9

Which of the following pairs of elements will most likely form an ionic bond?

Accepted Answer

$$\mathrm{Na}$$ and $$\mathrm{Cl}$$

Question 10

Which of the following is a diatomic element in its natural state?

Accepted Answer

$$\mathrm{O}_2$$

Question 11

What is the charge on an ion formed by an element in Group 2 of the periodic table?

Accepted Answer

$$+2$$

Question 12

Which of the following is a property of acids?

Accepted Answer

They turn blue litmus paper red.

Question 13

Calculate the formula mass of $$\mathrm{Na}_2\mathrm{SO}_4 ($$sodium sulfate). (Atomic masses: $$\mathrm{Na} = 23.0$$, $$\mathrm{S} = 32.1$$, $$\mathrm{O} = 16.0)$$

Accepted Answer

$$142.1$$

Question 14

Balance the following chemical equation: $$\mathrm{C}_2\mathrm{H}_6 + \mathrm{O}_2 \rightarrow \mathrm{CO}_2 + \mathrm{H}_2\mathrm{O}$$

Accepted Answer

$$2\mathrm{C}_2\mathrm{H}_6 + 7\mathrm{O}_2 \rightarrow 4\mathrm{CO}_2 + 6\mathrm{H}_2\mathrm{O}$$

Question 15

A reaction has a theoretical yield of $$10.0\ \mathrm{g}$$, but only $$7.5\ \mathrm{g} of $$product is actually obtained. What is the percent yield?

Accepted Answer

$$75\%$$

Question 16

A sample contains $$0.500\ \mathrm{mol} of$$ $$\mathrm{H}_2\mathrm{O}. $$What is the mass of this sample? (Molar mass of $$\mathrm{H}_2\mathrm{O} = 18.0\ \mathrm{g/mol})$$

Accepted Answer

$$9.0\ \mathrm{g}$$

Question 17

Which of the following conversion factors is correct for converting $$1\ \mathrm{km} to$$ $$\mathrm{m}$$?

Accepted Answer

$$1\ \mathrm{km} = 1000\ \mathrm{m}$$

Question 18

A reaction mixture contains $$5.0\ \mathrm{g} of$$ $$\mathrm{H}_2$$ and $$40.0\ \mathrm{g} of$$ $$\mathrm{O}_2. $$Which is the limiting reagent in the reaction $$2\mathrm{H}_2 + \mathrm{O}_2 \rightarrow 2\mathrm{H}_2\mathrm{O}$$?

Accepted Answer

$$\mathrm{H}_2$$

Question 19

Which of the following best describes what happens to electrons in a covalent bond?

Accepted Answer

Electrons are shared between atoms.

Question 20

Which of the following statements about Avogadro’s number is correct?

Accepted Answer

Avogadro’s number is $$6.022 	imes 10$$^{23}$$ and represents the number of particles in one mole.

General Chemistry Exam 1 Review: Matter, Measurement, Atoms, Molecules, and Chemical Reactions

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