Question 1

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

Accepted Answer

Atoms are rearranged, but the total number of each type of atom remains the same before and after the reaction.

Question 2

Given the unbalanced equation $$\mathrm{C_3H_8(g) + O_2$(g) \rightarrow CO_2$(g) + H_2O(g)}$$, what is the correct coefficient for $$\mathrm{O_2$}$$ when the equation is balanced?

Accepted Answer

5

Question 3

Which chemical equation correctly represents a combination (synthesis) reaction?

Accepted Answer

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

Question 4

In the reaction $$\mathrm{2KClO_3(s) \xrightarrow{\Delta} 2KCl(s) + 3O_2(g)}$$, what does the symbol $$\Delta$$ above the arrow indicate?

Accepted Answer

Heat is added to the reaction.

Question 5

Which of the following is a double replacement reaction?

Accepted Answer

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

Question 6

What is the correct balanced equation for the combustion of propane ($$\mathrm{C_3H_8}$$)?

Accepted Answer

$$\mathrm{C_3H_8(g) + 5O_2(g) \rightarrow 3CO_2(g) + 4H_2O(g)}$$

Question 7

In the equation $$\mathrm{SO_3$(g) + H_2O(l) \rightarrow H_2SO_4(aq)}$$, what does the (aq) state symbol mean?

Accepted Answer

The substance is dissolved in water.

Question 8

Which of the following reactions is a decomposition reaction?

Accepted Answer

$$\mathrm{2KClO_3(s) \xrightarrow{\Delta} 2KCl(s) + 3O_2(g)}$$

Question 9

Which of the following is true about coefficients in a chemical equation?

Accepted Answer

They are placed in front of chemical formulas to show how many units participate in the reaction.

Question 10

A student writes the equation $$\mathrm{H_2$ + O_2$ \rightarrow H_2O}. $$What is the main error in this equation?

Accepted Answer

The equation is not balanced; the number of oxygen atoms is not the same on both sides.

Question 11

Which of the following best describes a single replacement reaction?

Accepted Answer

One element replaces another in a compound.

Question 12

In the reaction $$\mathrm{Zn(s) + 2HCl(aq) \rightarrow $$ZnCl_2$$(aq) + H_2$(g)}$$, which element is oxidized?

Accepted Answer

Zinc

Question 13

Which of the following is a redox reaction?

Accepted Answer

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

Question 14

Which of the following is the correct balanced equation for the reaction between ammonia and hydrochloric acid?

Accepted Answer

$$\mathrm{NH_3$ + HCl \rightarrow NH_4Cl}$$

Question 15

Which of the following best describes the physical state symbol (s) in a chemical equation?

Accepted Answer

The substance is a solid.

Question 16

In the reaction $$\mathrm{2H_2O(l) \rightarrow 2H_2(g) + O_2$(g)}$$, what type of reaction is this?

Accepted Answer

Decomposition

Question 17

Which of the following is a correct statement about balancing chemical equations?

Accepted Answer

The number of atoms of each element must be the same on both sides of the equation.

Question 18

Which of the following is a combustion reaction?

Accepted Answer

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

Question 19

A chemical equation is balanced when:

Accepted Answer

The number of atoms of each element is equal on both sides of the equation.

Chemical Equations and Types of Chemical Reactions

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