Question 1

Which of the following best describes the purpose of significant figures in chemical measurements?

Accepted Answer

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

Question 2

A student measures the mass of a sample as 12.30 g and its volume as 4.1 mL. What is the density of the sample, reported with the correct number of significant figures?

Accepted Answer

$$3.0\ \mathrm{g/mL}$$

Question 3

Which of the following is NOT a physical property of matter?

Accepted Answer

Reactivity with oxygen

Question 4

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

Accepted Answer

Atomic number defines the identity of an element and its chemical properties.

Question 5

A compound contains 40% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 6

Which of the following best describes a chemical change?

Accepted Answer

Iron rusting when exposed to air

Question 7

A sample of gas at 1.00 atm and 273 K occupies 22.4 L. If the temperature is increased to 546 K at constant pressure, what will be the new volume?

Accepted Answer

$$44.8\ \mathrm{L}$$

Question 8

Which of the following best explains why ionic compounds conduct electricity when dissolved in water?

Accepted Answer

The ions are free to move and carry charge in solution.

Question 9

Which of the following is the correct balanced equation for the reaction of acetic acid ($$\mathrm{CH_3COOH}) $$with sodium hydroxide ($$\mathrm{NaOH}$$)?

Accepted Answer

$$\mathrm{CH_3COOH} + \mathrm{NaOH} \rightarrow \mathrm{CH_3COONa} + \mathrm{H_2O}$$

Question 10

A solution is prepared by dissolving 0.5 mol of NaCl in enough water to make 1.0 L of solution. What is the molarity of the solution?

Accepted Answer

$$0.50\ \mathrm{M}$$

Question 11

Which of the following best describes the difference between a covalent and an ionic bond?

Accepted Answer

Covalent bonds involve sharing electrons, while ionic bonds involve transferring electrons.

Question 12

Which gas law explains why a balloon expands when heated?

Accepted Answer

Charles's Law: $$\frac{V_1$}{T_1$} = \frac{V_2$}{T_2$}$$

Question 13

Which of the following is the correct formula for calcium phosphate?

Accepted Answer

$$\mathrm{Ca_3$(PO_4$)_2}$$

Question 14

A student titrates 25.0 mL of acetic acid with 0.100 M NaOH. If the endpoint is reached after adding 30.0 mL of NaOH, what is the concentration of the acetic acid?

Accepted Answer

$$0.120\ \mathrm{M}$$

Question 15

Which of the following best describes the kinetic molecular theory of gases?

Accepted Answer

Gas particles are in constant, random motion and collisions are elastic.

Question 16

Which of the following is a correct statement about the law of conservation of mass?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 17

Which of the following best explains why water is a polar molecule?

Accepted Answer

Water has a bent shape and an unequal distribution of electrons.

Question 18

Which of the following is the correct net ionic equation for the reaction between silver nitrate and sodium chloride?

Accepted Answer

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

Question 19

Which of the following best describes the difference between an empirical formula and a molecular formula?

Accepted Answer

An empirical formula shows the simplest whole-number ratio of atoms, while a molecular formula shows the actual number of atoms in a molecule.

Introduction to Chemistry: Course Syllabus and Topic Overview

Guida di studio - Domande di pratica

Study guide - Flashcard