Question 1

Which of the following statements best describes a compound?

Accepted Answer

A substance composed of two or more elements chemically combined in a fixed ratio.

Question 2

Which of the following is an example of an ionic bond?

Accepted Answer

The bond between sodium and chlorine in $$\mathrm{NaCl}.$$

Question 3

A student measures the mass of a metal block as $$45.67\ \mathrm{g}$$ and its volume as $$12.3\ \mathrm{cm^3$}. $$What is the density of the metal, reported with the correct number of significant figures?

Accepted Answer

$$3.71\ \mathrm{g/cm^3$}$$

Question 4

Which of the following is NOT an SI base unit?

Accepted Answer

Gram

Question 5

Which statement correctly describes the location of subatomic particles in an atom?

Accepted Answer

Protons and neutrons are in the nucleus; electrons orbit the nucleus.

Question 6

A chemist combines 10.0 g of hydrogen with 80.0 g of oxygen to form water. Which statement best explains why water is classified as a compound?

Accepted Answer

It is composed of two elements chemically combined in a fixed ratio.

Question 7

Which of the following best explains why the periodic table is organized by atomic number rather than atomic mass?

Accepted Answer

Atomic number reflects the number of protons, which defines the element.

Question 8

Which of the following measurements contains the correct number of significant figures?

Accepted Answer

0.04050 (4 significant figures)

Question 9

A sample of gas has a mass of $$2.50\ \mathrm{g}$$ and occupies a volume of $$1.20\ \mathrm{L}. $$What is its density in $$\mathrm{g/L}$$?

Accepted Answer

$$2.08\ \mathrm{g/L}$$

Question 10

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of electron pairs between atoms.

Question 11

A student records the following measurements: $$2.00\ \mathrm{m}$$, $$0.020\ \mathrm{m}$$, and $$0.0020\ \mathrm{m}. $$How many significant figures are in the sum of these measurements?

Accepted Answer

2

Question 12

Which of the following is a pure substance?

Accepted Answer

Carbon dioxide ($$\mathrm{CO_2$})$$

Question 13

A patient receives a dose of medication that is $$0.250\ \mathrm{g} in $$mass. If the density of the medication is $$1.25\ \mathrm{g/mL}$$, what volume in $$\mathrm{mL}$$ should be administered?

Accepted Answer

$$0.200\ \mathrm{mL}$$

Question 14

Which of the following best describes the difference between a solid and a gas at the particle level?

Accepted Answer

Particles in a solid are closely packed and vibrate; particles in a gas are far apart and move freely.

Question 15

Which of the following is the correct formula for density?

Accepted Answer

$$d = \dfrac{m}{V}$$

Question 16

Which of the following is a correct statement about elements?

Accepted Answer

Elements are pure substances that cannot be broken down by chemical means.

Question 17

A laboratory technician needs to prepare $$250.0\ \mathrm{mL} of a $$solution. If the solution must contain $$5.00\ \mathrm{g} of $$solute, what is the concentration in $$\mathrm{g/L}$$?

Accepted Answer

$$20.0\ \mathrm{g/L}$$

Question 18

Which of the following best explains why significant figures are important in scientific measurements?

Accepted Answer

They express the precision of a measurement and help communicate uncertainty.

Question 19

Which of the following is the correct SI unit for the amount of substance?

Accepted Answer

Mole

Question 20

A sample contains $$6.02 	imes 10$$^{23}$$ atoms of carbon. Which SI unit best expresses the amount of substance in this sample?

Accepted Answer

Mole

Question 21

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

Accepted Answer

A pure substance has a fixed composition; a mixture has variable composition.

Matter, Measurement, and Atomic Structure: General Chemistry Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard