Question 1

Which of the following is NOT a visible sign of a chemical reaction?

Accepted Answer

Dissolving sugar in water

Question 2

What is the balanced chemical equation for the combustion of methane ($$CH_4) in $$oxygen?

Accepted Answer

$$CH_4(g) + 2O_2(g$$) \rightarrow $$CO_2(g) + 2H_2O(g$$)$$

Question 3

Which type of chemical reaction is represented by the following equation? $$2KClO_3(s) \rightarrow 2KCl(s) + 3O_2(g)$$

Accepted Answer

Decomposition

Question 4

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

Accepted Answer

$$Zn(s)$$

Question 5

Which of the following equations is NOT balanced?

Accepted Answer

$$Na(s) + N_2$(g) \rightarrow Na_3N(s)$$

Question 6

Which of the following best describes a double-replacement reaction?

Accepted Answer

Two compounds exchange ions to form two new compounds

Question 7

What is the correct coefficient for $$NaCl$$ when balancing the equation: $$Na_3PO_4(aq) + $$MgCl_2$$(aq) \rightarrow Mg_3$(PO_4$)_2(s) + NaCl(aq)$$?

Accepted Answer

6

Question 8

Which of the following is an example of a combination reaction?

Accepted Answer

$$Mg(s) + O_2$(g) \rightarrow 2MgO(s)$$

Question 9

In a redox reaction, which statement is TRUE?

Accepted Answer

Oxidation is the loss of electrons and reduction is the gain of electrons

Question 10

Which of the following reactions is a combustion reaction?

Accepted Answer

$$C_4H_{10}(g) + 13O_2(g) \rightarrow 8CO_2(g) + 10H_2O(g)$$

Question 11

When balancing the equation $$CH_4(g$$) + $$O_2(g$$) \rightarrow $$CO_2(g) + H_2O(g$$)$$, what is the first element you should balance?

Accepted Answer

Carbon

Question 12

Which of the following is the correct balanced equation for the reaction of aluminum with iron(III) oxide?

Accepted Answer

$$2Al(s) + Fe_2O_3(s) \rightarrow 2Fe(s) + Al_2O_3(s)$$

Question 13

Which of the following is a single-replacement reaction?

Accepted Answer

$$Zn(s) + 2HCl(aq) \rightarrow $$ZnCl_2$$(aq) + H_2$(g)$$

Question 14

Which of the following best describes what happens during oxidation in a redox reaction?

Accepted Answer

An atom loses electrons

Question 15

A student mixes baking soda ($$NaHCO_3) $$and vinegar ($$CH_3COOH) $$and observes bubbles forming. What is the best explanation for this observation?

Accepted Answer

A chemical reaction produced a gas

Question 16

Which of the following is the correct balanced equation for the reaction: $$P_4(s$$) + $$Br_2(l$$) \rightarrow $$PBr_3(g$$)$$?

Accepted Answer

$$P_4(s) + 6Br_2(l$$) \rightarrow 4PBr_3(g)$$

Question 17

Which of the following reactions is a decomposition reaction?

Accepted Answer

$$2HgO(s) \rightarrow 2Hg(l) + O_2$(g)$$

Question 18

In the reaction $$2Cu(s) + O_2$(g) \rightarrow 2CuO(s)$$, which element is reduced?

Accepted Answer

Oxygen

Question 19

Which of the following is a correct description of a chemical change?

Accepted Answer

A substance is converted into one or more new substances

Chapter 8: Chemical Reactions – Evidence, Equations, and Types

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