Question 1

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

Accepted Answer

An element is a pure substance consisting of only one type of atom, while a compound consists of two or more different elements chemically bonded together.

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

8

Question 3

Which of the following best explains why water molecules are polar?

Accepted Answer

The oxygen atom is more electronegative than hydrogen, causing an unequal sharing of electrons and a partial negative charge on oxygen.

Question 4

Which emergent property of water allows insects to walk on its surface?

Accepted Answer

Cohesion

Question 5

If the pH of a solution changes from 5 to 3, by what factor does the concentration of hydrogen ions change?

Accepted Answer

$10^2$

Question 6

Which of the following best describes a buffer’s role in biological systems?

Accepted Answer

Buffers maintain a stable pH by absorbing excess hydrogen or hydroxide ions.

Question 7

Which of the following ions are produced when water dissociates?

Accepted Answer

H$^+$ and OH$^-$

Question 8

A sodium atom (Na) has 11 protons, 12 neutrons, and 10 electrons. What is its charge and what is it called?

Accepted Answer

It has a $+1$ charge and is called a cation.

Question 9

Which type of chemical bond involves the sharing of electron pairs between atoms?

Accepted Answer

Covalent bond

Question 10

Which property of water is most important for the transport of water from roots to leaves in plants?

Accepted Answer

Cohesion and adhesion

Question 11

A solution is made by dissolving salt in water. Which term best describes the salt?

Accepted Answer

Solute

Question 12

Which of the following substances is most likely to be hydrophobic?

Accepted Answer

Olive oil

Question 13

Which statement correctly compares two isotopes of the same element?

Accepted Answer

They have the same number of protons but different numbers of neutrons.

Question 14

Which of the following best describes the difference between cohesion and adhesion?

Accepted Answer

Cohesion is the attraction between like molecules, while adhesion is the attraction between different molecules.

Question 15

A fluorine atom has an atomic number of 9 and a mass number of 19. How many electrons are in its valence shell?

Accepted Answer

7

Question 16

Which of the following is true about hydrogen bonds?

Accepted Answer

They occur between molecules with polar covalent bonds.

Question 17

If a solution has a pH of 2, which of the following best describes its properties?

Accepted Answer

It is acidic and has a high concentration of H$^+$ ions.

Question 18

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

Accepted Answer

An atom gains or loses electrons.

Question 19

A scientist finds two samples of oxygen: one with a mass number of 16 and one with a mass number of 18. What is the difference between these two samples?

Accepted Answer

They have different numbers of neutrons.

Question 20

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

Accepted Answer

Ice is less dense than liquid water because hydrogen bonds hold water molecules further apart in the solid state.

General Biology: Chemistry Foundations (Chapter 2 Study Guide)

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