Q: Which equation correctly represents the law of conservation of mass in a chemical reaction?

$$\text{Total mass of reactants} = \text{Total mass of products}$$

Q: A sample contains 3.0 moles of oxygen molecules ($$\mathrm{O_2$}). $$How many molecules are present in the sample? (Avogadro's number $$= 6.02 \times 10$$^{23}$$)

$$1.81 \times 10$$^{24}$$ molecules

Q: Which equation represents the relationship between mass, volume, and density?

$$\text{Density} = \frac{\text{Mass}}{\text{Volume}}$$

Question 1

Which of the following best describes a chemical compound?

Accepted Answer

A substance formed when two or more elements are chemically bonded in fixed proportions.

Question 2

Which equation correctly represents the law of conservation of mass in a chemical reaction?

Accepted Answer

$$	ext{Total mass of reactants} = 	ext{Total mass of products}$$

Question 3

A student mixes hydrochloric acid ($$\mathrm{HCl}) $$with sodium hydroxide ($$\mathrm{NaOH}) in a $$beaker. Which type of chemical reaction is this?

Accepted Answer

Acid-base neutralization reaction

Question 4

Which of the following is NOT a property of acids?

Accepted Answer

They feel slippery to the touch.

Question 5

Which model best explains the structure of the atom as described in introductory chemistry?

Accepted Answer

Bohr model

Question 6

A sample contains 3.0 moles of oxygen molecules ($$\mathrm{O_2$}). $$How many molecules are present in the sample? (Avogadro's number $$= 6.02 	imes 10$$^{23}$$)

Accepted Answer

$$1.81 	imes 10$$^{24}$$ molecules

Question 7

Which of the following is a chemical change?

Accepted Answer

Burning wood

Question 8

Which equation represents the relationship between mass, volume, and density?

Accepted Answer

$$	ext{Density} = \frac{	ext{Mass}}{	ext{Volume}}$$

Question 9

Which of the following best describes oxidation in a chemical reaction?

Accepted Answer

Loss of electrons by a substance

Question 10

A solution is prepared by dissolving 10 g of salt in 90 g of water. What is the mass percent of salt in the solution?

Accepted Answer

$$10\%$$

Question 11

Which of the following statements about chemical bonds is correct?

Accepted Answer

Ionic bonds are formed by transferring electrons from one atom to another.

Question 12

Which of the following is an example of a molecular compound?

Accepted Answer

Water ($$\mathrm{H_2O})$$

Question 13

Which of the following hazards is most commonly associated with chemical reactions in the laboratory?

Accepted Answer

Risk of fire or explosion

Question 14

Which of the following is the correct electron configuration for a neutral carbon atom ($$Z=6$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^2$$

Question 15

A chemical reaction has the following balanced equation: $$2\mathrm{H_2$} + \mathrm{O_2$} \rightarrow 2\mathrm{H_2O}. If $$you start with 4 moles of $$\mathrm{H_2$}$$ and excess $$\mathrm{O_2$}$$, how many moles of $$\mathrm{H_2O}$$ will be produced?

Accepted Answer

4 moles

Question 16

Which of the following is a correct statement about solutions?

Accepted Answer

A solution consists of a solute dissolved in a solvent.

Question 17

Which of the following is the best example of a redox reaction?

Accepted Answer

Combustion of methane ($$\mathrm{CH_4$}) in $$oxygen

Question 18

Which of the following is the correct formula for calculating percent error in a laboratory experiment?

Accepted Answer

$$	ext{Percent Error} = \frac{|	ext{Experimental Value} - 	ext{Accepted Value}|}{	ext{Accepted Value}} 	imes 100\%$$

Question 19

A student is asked to identify the type of matter in a sample of air. Which classification is most appropriate?

Accepted Answer

Mixture

Question 20

Which of the following best describes the role of a catalyst in a chemical reaction?

Accepted Answer

It speeds up the reaction without being consumed.

CHEM 1010: Introduction to Chemistry I – Syllabus and Study Guide

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