Question 1

Which of the following is NOT evidence that a chemical reaction has occurred?

Accepted Answer

A change in shape

Question 2

Which of the following best describes the law of conservation of mass as it applies to chemical reactions?

Accepted Answer

The total mass of reactants equals the total mass of products.

Question 3

What type of reaction is represented by the following equation? $$2H_2 + O_2$ \rightarrow 2H_2O$$

Accepted Answer

Synthesis (combination)

Question 4

Which of the following is the correct balanced equation for the combustion of propane ($$C_3H_8$$)?

Accepted Answer

$$C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O$$

Question 5

A student mixes solutions of $$KI$$ and $$Pb(NO_3$)_2$$ and observes a yellow solid forming. What is the net ionic equation for this reaction?

Accepted Answer

$$Pb^{2+}(aq) + 2I^-(aq$$) \rightarrow $$PbI_2(s$$)$$

Question 6

Which of the following compounds is insoluble in water according to the solubility rules?

Accepted Answer

$$PbSO_4$$

Question 7

What is the driving force for the following reaction? $$HCl(aq) + NaOH(aq) \rightarrow NaCl(aq) + H_2O(l)$$

Accepted Answer

Formation of water

Question 8

Which of the following best describes an oxidation-reduction (redox) reaction?

Accepted Answer

A reaction in which electrons are transferred between species

Question 9

In the reaction $$Zn(s) + Cu$$^{2+}$$(aq) \rightarrow Zn$$^{2+}$$(aq) + Cu(s)$$, which species is oxidized?

Accepted Answer

$$Zn$$

Question 10

Which of the following is a correct net ionic equation for the reaction between $$HCl(aq)$$ and $$NaOH(aq)$$?

Accepted Answer

$$H^+(aq) + OH^-(aq) \rightarrow H_2O(l)$$

Question 11

A student observes bubbles forming when zinc metal is added to hydrochloric acid. Which driving force is responsible for this reaction?

Accepted Answer

Formation of a gas

Question 12

Which of the following reactions is a decomposition reaction?

Accepted Answer

$$2NaCl \rightarrow 2Na + Cl_2$

Question 13

Which of the following is a correct balanced equation for the reaction of solid potassium with water?

Accepted Answer

$$2K(s) + 2H_2O(l) \rightarrow 2KOH(aq) + H_2$(g)$$

Question 14

Which of the following is a spectator ion in the reaction between $$Pb(NO_3$)_2(aq)$$ and $$Na_2SO_4(aq)$$?

Accepted Answer

$$Na^+$$

Question 15

Which of the following best describes a precipitation reaction?

Accepted Answer

A reaction in which a solid forms from two aqueous solutions

Question 16

Which of the following is the correct net ionic equation for the formation of a precipitate when $$BaCl_2(aq$$)$$ is mixed with Na_2SO_4(aq$$)$$?

Accepted Answer

$$Ba^{2+}(aq$$) + $$SO_4$$^{2-}(aq) \rightarrow $$BaSO_4(s$$)$$

Question 17

Which of the following is a double replacement reaction?

Accepted Answer

$$NaCl + $$AgNO_3$$ \rightarrow $$NaNO_3$$ + AgCl$$

Question 18

Which of the following best describes the role of $$Zn in $$the reaction $$Zn(s) + Cu$$^{2+}$$(aq) \rightarrow Zn$$^{2+}$$(aq) + Cu(s)$$?

Accepted Answer

Reducing agent

Question 19

Which of the following is a correct statement about redox reactions?

Accepted Answer

Oxidation and reduction always occur together.

Question 20

Which of the following is the correct balanced equation for the reaction: $$Fe(s) + O_2$(g) \rightarrow Fe_2O_3(s)$$?

Accepted Answer

$$4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)$$

Chapter 7: Chemical Reactions – Types, Evidence, and Equations

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