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 visibly distinguished, such as sand in water.

Question 2

A student measures the mass of a sample three times and records the following values: 5.12 g, 5.13 g, and 5.11 g. The true mass is 5.50 g. Which statement best describes the accuracy and precision of these measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 3

Which of the following is a chemical property?

Accepted Answer

Reactivity with oxygen

Question 4

A sample contains 3.0 moles of sodium chloride ($$\mathrm{NaCl}). $$What is the mass of this sample? ($$\mathrm{Na} = 23.0\ \mathrm{g/mol}$$, $$\mathrm{Cl} = 35.5\ \mathrm{g/mol})$$

Accepted Answer

$$175.5\ \mathrm{g}$$

Question 5

Which of the following best explains why ice floats on water?

Accepted Answer

Ice has a lower density than liquid water due to its molecular structure.

Question 6

Which of the following is the correct nuclear equation for the alpha decay of uranium-238 ($$^{238}_{92}\mathrm{U}$$)?

Accepted Answer

$$^{238}_{92}\mathrm{U} \$$rightarrow ^{234}$$_{90}\mathrm{Th} $$+ ^{4}$$_{2}\mathrm{He}$$

Question 7

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 8

A student needs to convert $$2500\ \mathrm{mg} to $$grams using dimensional analysis. What is the correct answer?

Accepted Answer

$$2.5\ \mathrm{g}$$

Question 9

Which of the following best describes the Law of Conservation of Energy?

Accepted Answer

Energy cannot be created or destroyed, only transformed from one form to another.

Question 10

Which of the following is a physical change?

Accepted Answer

Boiling water

Question 11

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

Accepted Answer

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

Question 12

Which of the following is NOT a method for separating mixtures?

Accepted Answer

Electrolysis

Question 13

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have the same number of valence electrons.

Question 14

Which of the following is the correct definition of an ion?

Accepted Answer

An atom or molecule with a net electric charge due to the loss or gain of electrons.

Question 15

Which of the following is a correct example of a physical property?

Accepted Answer

Boiling point

Question 16

A radioactive isotope decays by emitting a beta particle. Which of the following correctly describes the change in the nucleus?

Accepted Answer

The atomic number increases by 1, and the mass number remains the same.

Question 17

Which of the following best describes the difference between mass and weight?

Accepted Answer

Mass is the amount of matter in an object, while weight is the force of gravity acting on that mass.

Question 18

Which of the following is the correct order of electromagnetic radiation from lowest to highest energy?

Accepted Answer

Radio waves \u003c Infrared \u003c Visible \u003c Ultraviolet \u003c X-rays \u003c Gamma rays

Question 19

A sample of gas occupies $$2.0\ \mathrm{L} at$$ $$1.0\ \mathrm{atm}$$ pressure. If the pressure is increased to $$4.0\ \mathrm{atm} at $$constant temperature, what is the new volume of the gas? (Assume ideal gas behavior.)

Accepted Answer

$$0.5\ \mathrm{L}$$

Question 20

Which of the following best explains why nuclear fusion releases more energy than nuclear fission?

Accepted Answer

Fusion combines small nuclei into a larger nucleus, resulting in a greater mass defect and more energy released according to $$E=mc^2$.

Introduction to Chemistry: Key Concepts and Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards