Question 1

Which of the following statements best describes an element?

Accepted Answer

An element is a substance that cannot be broken down to another substance by chemical means.

Question 2

Which four elements make up approximately 96% of living matter?

Accepted Answer

Carbon, hydrogen, nitrogen, and oxygen

Question 3

A radioactive isotope differs from a stable isotope of the same element because it:

Accepted Answer

Has an unstable nucleus that decays, emitting radiation

Question 4

Which of the following best describes a covalent bond?

Accepted Answer

A bond in which two atoms share one or more pairs of electrons

Question 5

What is the main reason water molecules have a bent shape with a bond angle of approximately $$104.5^{\circ}$$?

Accepted Answer

The arrangement of electron pairs around the oxygen atom causes the molecule to adopt a bent shape

Question 6

Which of the following is true about chemical equilibrium?

Accepted Answer

The forward and reverse reactions occur at the same rate, so the concentrations of reactants and products do not change

Question 7

A cation is formed when an atom:

Accepted Answer

Loses one or more electrons

Question 8

Which of the following best explains why trace elements are important for living organisms?

Accepted Answer

They are required in very small amounts but are essential for proper biological function

Question 9

If an atom has an atomic number of 8 and a mass number of 18, how many neutrons does it have?

Accepted Answer

$$18 - 8 = 10$$ neutrons

Question 10

Which of the following statements about potential energy in atoms is correct?

Accepted Answer

Electrons have more potential energy when they are farther from the nucleus

Question 11

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a hydrogen atom covalently bonded to one electronegative atom and another electronegative atom

Question 12

Which of the following is an example of oxidation in a chemical reaction?

Accepted Answer

An atom loses electrons

Question 13

Which of the following best describes a polar covalent bond?

Accepted Answer

Electrons are shared unequally between two atoms, resulting in partial charges

Question 14

Which of the following is a real-life example of a van der Waals interaction?

Accepted Answer

A gecko climbing a wall due to weak attractions between its feet and the surface

Question 15

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 16

A molecule of $$\mathrm{H_2O}$$ has which of the following properties?

Accepted Answer

It has a bent shape due to two covalent bonds and two lone pairs on oxygen

Question 17

Which of the following best explains why chemical reactions are reversible?

Accepted Answer

The products can react to form the original reactants under certain conditions

Question 18

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

Accepted Answer

A substance consisting of two or more different elements combined in a fixed ratio

Question 19

Which of the following best describes the role of valence electrons in chemical bonding?

Accepted Answer

Valence electrons are the outermost electrons and are involved in forming chemical bonds

Question 20

A patient is injected with a radioactive isotope for medical imaging. Which property of the isotope allows it to be detected inside the body?

Accepted Answer

It emits radiation as it decays, which can be measured by imaging equipment

Ch. 2 study guide

Study Guide - Practice Questions