Q: A sample of ethanol has a density of 0.79 g/mL. What is the mass of 50.0 mL of ethanol?

$$m = 0.79\ \mathrm{g/mL} \times 50.0\ \mathrm{mL} = 39.5\ \mathrm{g}$$

Question 1

Which of the following best describes a compound?

Accepted Answer

A substance composed of atoms from two or more different elements in a fixed ratio.

Question 2

Which of the following is an example of a physical change?

Accepted Answer

Melting of ice to form liquid water.

Question 3

A sample of gold has a mass of 38.64 g and a volume of 2.00 cm$$^3. $$What is the density of gold in g/cm$$^3$$?

Accepted Answer

$$D = \frac{38.64\ \mathrm{g}}{2.00\ \mathrm{cm}^3} = 19.32\ \mathrm{g/cm}^3$$

Question 4

Which of the following is an intensive property?

Accepted Answer

Density

Question 5

A solution of salt water is an example of which classification of matter?

Accepted Answer

Homogeneous mixture

Question 6

Which separation technique would be most effective for separating a mixture of sand and salt water?

Accepted Answer

Filtration

Question 7

Which of the following is the correct SI base unit for temperature?

Accepted Answer

Kelvin (K)

Question 8

Convert 25.0 °C to Kelvin.

Accepted Answer

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

Question 9

Which of the following is a chemical property?

Accepted Answer

Flammability

Question 10

A student measures the mass of a sample three times and gets values of 2.45 g, 2.46 g, and 2.44 g. The true mass is 2.90 g. Which statement is correct?

Accepted Answer

The measurements are precise but not accurate.

Question 11

Which of the following is the correct conversion factor to change 5.00 inches to centimeters? (1 inch = 2.54 cm)

Accepted Answer

$$\frac{2.54\ \mathrm{cm}}{1\ \mathrm{in}}$$

Question 12

Which of the following is NOT a base SI unit?

Accepted Answer

Liter (L)

Question 13

A sample of ethanol has a density of 0.79 g/mL. What is the mass of 50.0 mL of ethanol?

Accepted Answer

$$m = 0.79\ \mathrm{g/mL} 	imes 50.0\ \mathrm{mL} = 39.5\ \mathrm{g}$$

Question 14

Which of the following statements about mixtures is TRUE?

Accepted Answer

Heterogeneous mixtures have visibly distinguishable parts.

Question 15

Which prefix represents $$10^{-6} in $$the metric system?

Accepted Answer

Micro-

Question 16

A chemical reaction occurs when copper reacts with nitric acid, producing a blue solution and a brown gas. Which property is most useful for identifying that a chemical change has occurred?

Accepted Answer

Change in color

Question 17

Which of the following is an example of an exact number?

Accepted Answer

The number of students in a classroom

Question 18

How many significant figures are in the number 0.004560?

Accepted Answer

4

Question 19

Which of the following best describes the Law of Constant Composition?

Accepted Answer

The relative number of atoms of each element in a compound is the same in any sample.

Question 20

A runner burns 500 nutritional Calories during a workout. How many kilojoules (kJ) is this? (1 nutritional Calorie = 1 kcal = 4.184 kJ)

Accepted Answer

$$500 	imes 4.184 = 2092\ \mathrm{kJ}$$

Chapter 1: Introduction to Matter, Energy, and Measurement – General Chemistry Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard