Question 1

Which of the following is NOT considered evidence of a chemical reaction?

Accepted Answer

Bubbles form when water boils.

Question 2

Which of the following best describes a precipitation reaction?

Accepted Answer

A reaction that forms a solid when two aqueous solutions are mixed.

Question 3

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

Accepted Answer

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

Question 4

Which of the following compounds is most likely to be insoluble in water?

Accepted Answer

$$\mathrm{AgCl}$$

Question 5

When sodium carbonate is added to hard water containing calcium ions, what type of reaction occurs?

Accepted Answer

A precipitation reaction forming $$\mathrm{$$CaCO_3$$(s)}$$

Question 6

Which of the following is a correct net ionic equation for the reaction between hydrochloric acid and sodium hydroxide?

Accepted Answer

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

Question 7

Which of the following reactions is an example of a redox reaction?

Accepted Answer

$$\mathrm{2Na(s) + Cl_2$(g) \rightarrow 2NaCl(s)}$$

Question 8

Which of the following best describes a strong electrolyte?

Accepted Answer

A substance that completely dissociates into ions in solution.

Question 9

What is the correct sequence of steps for balancing a chemical equation?

Accepted Answer

Write correct formulas, balance elements that appear in only one compound on each side, balance free elements last, check your work.

Question 10

Which of the following is a double-displacement reaction?

Accepted Answer

$$\mathrm{$$AgNO_3$$(aq) + NaCl(aq) \rightarrow AgCl(s) + $$NaNO_3$$(aq)}$$

Question 11

Which of the following statements about boiling water is correct?

Accepted Answer

Boiling water is a physical change, not a chemical reaction.

Question 12

Which of the following is the correct molecular equation for the reaction between potassium iodide and lead(II) nitrate in aqueous solution?

Accepted Answer

$$\mathrm{2KI(aq) + Pb(NO_3$)_2(aq) \rightarrow $$PbI_2$$(s) + 2KNO_3(aq)}$$

Question 13

Which of the following is a synthesis reaction?

Accepted Answer

$$\mathrm{2Na(s) + Cl_2$(g) \rightarrow 2NaCl(s)}$$

Question 14

Which of the following is the best definition of an acid–base reaction?

Accepted Answer

A reaction that forms water and a salt upon mixing an acid and a base.

Question 15

Which of the following is a correct complete ionic equation for the reaction between sodium sulfate and barium chloride in aqueous solution?

Accepted Answer

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

Question 16

Which of the following is a gas evolution reaction?

Accepted Answer

$$\mathrm{Na_2CO_3(aq) + 2HCl(aq) \rightarrow 2NaCl(aq) + H_2O(l) + CO_2$(g)}$$

Question 17

Which of the following best describes a decomposition reaction?

Accepted Answer

A complex substance breaks down into simpler substances.

Question 18

Which of the following is a spectator ion in the reaction $$\mathrm{$$AgNO_3$$(aq) + NaCl(aq) \rightarrow AgCl(s) + $$NaNO_3$$(aq)}$$?

Accepted Answer

$$\mathrm{NO_3$^-}$$

Chemical Reactions and Equations: Evidence, Types, and Balancing

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