Q: Which equation correctly represents the calculation for the molarity ($$M) of a $$solution?

$$M = \frac{\text{moles of solute}}{\text{liters of solution}}$$

Q: Which of the following is the correct formula for calculating percent error in a laboratory measurement?

$$\text{Percent Error} = \frac{\text{Experimental Value} - \text{Accepted Value}}{\text{Accepted Value}} \times 100\%$$

Question 1

Which of the following best describes the scientific method as applied in a chemistry laboratory?

Accepted Answer

A systematic approach involving observation, hypothesis, experimentation, and analysis.

Question 2

A student measures the mass of a sample as 12.34 g and its volume as 4.56 mL. What is the density of the sample, and what is the correct formula to use?

Accepted Answer

Density = mass / volume; $$Density = \frac{12.34}{4.56}$$

Question 3

Which of the following is a correct safety practice when working with chemicals in the laboratory?

Accepted Answer

Goggles must be worn at all times when handling chemicals or glassware.

Question 4

Which of the following best explains why the periodic table is organized into groups and periods?

Accepted Answer

To reflect recurring chemical properties and electron configurations.

Question 5

A reaction requires 2.0 moles of hydrogen gas ($$H_2) $$and 1.0 mole of oxygen gas ($$O_2) to $$produce water. What is the balanced chemical equation for this reaction?

Accepted Answer

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

Question 6

Which equation correctly represents the calculation for the molarity ($$M) of a $$solution?

Accepted Answer

$$M = \frac{	ext{moles of solute}}{	ext{liters of solution}}$$

Question 7

A sample of gas occupies 2.0 L at 1.0 atm and 300 K. If the pressure is increased to 2.0 atm at constant temperature, what will be the new volume? (Use Boyle’s Law: $$P_1V_1 = P_2V_2)$$

Accepted Answer

1.0 L

Question 8

Which of the following statements about acids and bases is correct?

Accepted Answer

Bases increase the concentration of $$OH^-$$ ions in water.

Question 9

A radioactive isotope has a half-life of 10 years. If you start with 80 grams, how much remains after 30 years?

Accepted Answer

10 grams

Question 10

Which of the following best describes a buffer solution?

Accepted Answer

A solution that resists changes in pH when small amounts of acid or base are added.

Question 11

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

Accepted Answer

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

Question 12

Which of the following is a property of ionic compounds?

Accepted Answer

They conduct electricity when dissolved in water.

Question 13

A solution is prepared by dissolving 5.0 g of NaCl in enough water to make 250 mL of solution. What is the molarity of the solution? ($$M = \frac{	ext{moles}}{	ext{liters}}$$, molar mass NaCl = 58.44 g/mol)

Accepted Answer

0.34 M

Question 14

Which of the following best describes the difference between a physical and a chemical change?

Accepted Answer

A chemical change results in the formation of new substances.

Question 15

Which of the following is the correct equation for the relationship between Celsius and Kelvin temperatures?

Accepted Answer

$$K = ^\circ C + 273.15$$

Question 16

A student needs to prepare 100 mL of a 0.5 M NaOH solution from a 2.0 M stock solution. What volume of the stock solution should be used? (Use $$M_1V_1 = M_2V_2)$$

Accepted Answer

25 mL

Question 17

Which of the following is a correct statement about the behavior of gases according to the kinetic molecular theory?

Accepted Answer

Gas particles are in constant, random motion.

Question 18

Which of the following is the correct net ionic equation for the reaction between aqueous solutions of NaCl and AgNO$$_3$$?

Accepted Answer

$$Ag^+ (aq) + Cl^- (aq) \rightarrow AgCl (s)$$

Question 19

Which of the following is a correct statement about isotopes?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 20

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

Accepted Answer

It speeds up the reaction by lowering the activation energy.

General Chemistry Syllabus and Study Guide – Moraine Park Technical College

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