Question 1

Which of the following is a chemical change?

Accepted Answer

Burning wood

Question 2

Which observation is NOT evidence of a chemical change?

Accepted Answer

Change in state from solid to liquid

Question 3

In the reaction $$2CO_2 \rightarrow 2CO + O_2$, how many molecules of CO$ are produced?

Accepted Answer

2

Question 4

Which of the following best describes a physical change?

Accepted Answer

The form or state of a substance changes, but its chemical composition remains the same

Question 5

Which of the following is NOT an acid?

Accepted Answer

NaOH

Question 6

What is the correct balanced equation for the reaction: $$Na + Cl_2$ \rightarrow NaCl$$?

Accepted Answer

$$2Na + Cl_2$ \rightarrow 2NaCl$$

Question 7

Which of the following is a sign that a chemical reaction has occurred?

Accepted Answer

All of the above

Question 8

When zinc reacts with hydrochloric acid, what gas is produced?

Accepted Answer

Hydrogen

Question 9

Which test can you use to determine the presence of carbon dioxide gas in a reaction?

Accepted Answer

Bubble the gas through limewater; it will turn cloudy

Question 10

Which of the following reactions is a decomposition reaction?

Accepted Answer

$$CaCO_3$$ \rightarrow CaO + $$CO_2$$

Question 11

Which of the following is the correct classification for the reaction $$2Na + Cl_2$ \rightarrow 2NaCl$$?

Accepted Answer

Synthesis

Question 12

What is the difference between a coefficient and a subscript in a chemical equation?

Accepted Answer

A coefficient indicates the number of molecules or formula units; a subscript indicates the number of atoms in a molecule

Question 13

Which of the following is a double displacement reaction?

Accepted Answer

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

Question 14

A student mixes vinegar and baking soda. Which evidence best supports that a chemical change has occurred?

Accepted Answer

Bubbles of gas are produced

Question 15

Which of the following is the correct balanced equation for the reaction: $$Zn + HCl \rightarrow $$ZnCl_2$$ + H_2$?

Accepted Answer

$$Zn + 2HCl \rightarrow $$ZnCl_2$$ + H_2$

Question 16

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

Accepted Answer

Change in shape

Question 17

When balancing the equation $$2H_2 + O_2$ \rightarrow 2H_2O$$, which law is being followed?

Accepted Answer

Law of Conservation of Mass

Question 18

Which of the following best describes the products of the reaction: $$ZnCO_3 + 2$$HCl \rightarrow $$ZnCl_2 + H_2O$$ + $$CO_2$$?

Accepted Answer

A metal salt, water, and carbon dioxide gas

Question 19

Which of the following is a synthesis reaction?

Accepted Answer

$$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 20

A student observes a color change and formation of a precipitate when mixing two solutions. What type of change has occurred?

Accepted Answer

Chemical change

Physical and Chemical Changes, Chemical Equations, and Reactions in General Chemistry

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