Question 1

Which of the following best describes the difference between an element and a compound?

Accepted Answer

An element is a substance that cannot be broken down into other substances by chemical means, while a compound consists of two or more elements chemically combined in a fixed ratio.

Question 2

A neutral atom of carbon has an atomic number of 6 and a mass number of 14. How many neutrons does it have?

Accepted Answer

$$14 - 6 = 8$$ neutrons

Question 3

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 4

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

Accepted Answer

Oxygen is more electronegative than hydrogen, causing an unequal sharing of electrons and resulting in partial charges on the molecule.

Question 5

Which of the following is a property of water that results directly from hydrogen bonding?

Accepted Answer

High specific heat capacity

Question 6

If the pH of a solution changes from 5 to 2, how does the concentration of hydrogen ions change?

Accepted Answer

It increases by $$10^{3} = 1000$ times

Question 7

Which of the following best describes the difference between covalent, ionic, and hydrogen bonds?

Accepted Answer

Covalent bonds involve sharing electrons, ionic bonds involve transferring electrons, and hydrogen bonds are weak attractions between polar molecules.

Question 8

A sodium atom (Na) has 11 protons and 12 neutrons. What is its mass number?

Accepted Answer

$$11 + 12 = 23$$

Question 9

Which of the following best describes a buffer and its biological importance?

Accepted Answer

A buffer minimizes changes in pH by accepting or donating hydrogen ions, helping maintain homeostasis in organisms.

Question 10

Which of the following best explains why oil does not dissolve in water?

Accepted Answer

Oil is hydrophobic because it is nonpolar and cannot form hydrogen bonds with water.

Question 11

A solution is made by dissolving salt in water. In this scenario, which is the solute and which is the solvent?

Accepted Answer

Salt is the solute; water is the solvent.

Question 12

Which of the following is an example of adhesion in water?

Accepted Answer

Water droplets sticking to the surface of a leaf

Question 13

If an atom has 17 protons, 18 neutrons, and 17 electrons, what is its atomic number?

Accepted Answer

$$17$$

Question 14

Which of the following ions are produced when water dissociates?

Accepted Answer

Hydrogen ion ($$H^+) $$and hydroxide ion ($$OH^-)$$

Question 15

Which of the following best describes the relationship between atomic number, mass number, and number of neutrons?

Accepted Answer

Number of neutrons = mass number - atomic number

Question 16

Which of the following is a real-life example of water's high heat of vaporization being biologically important?

Accepted Answer

Sweating cools the human body as water evaporates from the skin, removing heat.

Question 17

A fluorine atom has 9 electrons. How many electrons are in its outer (valence) shell?

Accepted Answer

7

Question 18

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

Accepted Answer

Hydrogen bonds in ice create a lattice structure that is less dense than liquid water.

Question 19

Which of the following scenarios would most likely result in the formation of an ion?

Accepted Answer

A sodium atom loses an electron to a chlorine atom, forming $$Na^+$$ and $$Cl^-.$$

Question 20

Which of the following best describes the emergent property of cohesion in water?

Accepted Answer

Cohesion is the tendency of water molecules to stick to each other due to hydrogen bonding.

Chapter 2: Chemistry – Study Guide and Key Concepts for General Biology

Guida di studio - Domande di pratica

Study guide - Flashcard