$$\frac{\text{experimental value} - \text{accepted value}}{\text{accepted value}} \times 100\%$$

$$250\ \mathrm{mL} \times \frac{0.90\ \mathrm{g}}{100\ \mathrm{mL}} = 2.25\ \mathrm{g}$$

$$q = m \times c \times \Delta T$$

Question 1

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture in which the components are not evenly distributed and can be visually distinguished.

Question 2

A sample of a liquid has a mass of 45.0 g and a volume of 30.0 mL. What is its density?

Accepted Answer

$$\frac{45.0\ \mathrm{g}}{30.0\ \mathrm{mL}} = 1.5\ \mathrm{g/mL}$$

Question 3

Which of the following is NOT a physical property?

Accepted Answer

Ability to rust

Question 4

A student measures the temperature of a solution as 25.0°C. What is this temperature in Kelvin?

Accepted Answer

$$25.0 + 273.15 = 298.15\ \mathrm{K}$$

Question 5

Which of the following statements about atoms is correct?

Accepted Answer

Protons have a positive charge and neutrons are neutral.

Question 6

How many significant figures are in the measurement 0.00420?

Accepted Answer

3

Question 7

Which of the following best describes an endothermic process?

Accepted Answer

A process in which energy is absorbed from the surroundings.

Question 8

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

Accepted Answer

10 g

Question 9

Which of the following elements is a metalloid?

Accepted Answer

Silicon (Si)

Question 10

Which of the following is the correct electron configuration for a neutral atom of carbon (atomic number 6)?

Accepted Answer

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

Question 11

Which of the following is the correct formula for calculating percent error?

Accepted Answer

$$\frac{	ext{experimental value} - 	ext{accepted value}}{	ext{accepted value}} 	imes 100\%$$

Question 12

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

Metals have delocalized electrons that can move freely.

Question 13

A patient receives 250 mL of a saline solution with a concentration of 0.90% NaCl. How many grams of NaCl did the patient receive?

Accepted Answer

$$250\ \mathrm{mL} 	imes \frac{0.90\ \mathrm{g}}{100\ \mathrm{mL}} = 2.25\ \mathrm{g}$$

Question 14

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 15

Which of the following is the correct formula for calculating the energy change when heating a substance?

Accepted Answer

$$q = m 	imes c 	imes \Delta T$$

Question 16

Which of the following best describes the trend in atomic radius across a period in the periodic table?

Accepted Answer

Atomic radius decreases from left to right.

Question 17

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula?

Accepted Answer

$$\mathrm{CH}_2\mathrm{O}$$

Question 18

Which of the following is the correct definition of a mole?

Accepted Answer

The amount of substance that contains $$6.022 	imes 10$$^{23}$$ particles.

Question 19

Which of the following best describes the difference between a compound and a mixture?

Accepted Answer

A compound is made of two or more elements chemically combined, while a mixture is a physical blend of substances.

Question 20

Which of the following best explains why noble gases are chemically inert?

Accepted Answer

They have a full valence electron shell, making them stable.

GOB Chemistry Study Guide: Key Concepts and Calculations

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