Question 1

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

Accepted Answer

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

Question 2

A nitrogen atom has 7 protons and 9 neutrons. What is its atomic number and mass number?

Accepted Answer

Atomic number: 7, Mass number: 16

Question 3

Which equation correctly represents the chemical reaction that leads to ocean acidification?

Accepted Answer

$$CO_2 + H_2O$$ \rightarrow H_2CO_3$$

Question 4

Which property of water allows sweat to cool your skin after a workout?

Accepted Answer

Evaporative cooling due to hydrogen bonding

Question 5

What type of chemical bond is formed when one atom donates an electron to another atom?

Accepted Answer

Ionic bond

Question 6

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

Accepted Answer

A substance that minimizes changes in pH by accepting or donating H$$^+$$ ions

Question 7

Why is water considered the 'solvent of life'?

Accepted Answer

Water's polarity allows it to dissolve many ionic and polar substances.

Question 8

Which of the following is a trace element commonly added to municipal water to prevent disease?

Accepted Answer

Fluoride

Question 9

A controlled experiment on coral reefs measured the effect of carbonate ion concentration on calcification rate. What is the independent variable?

Accepted Answer

Carbonate ion concentration

Question 10

Which of the following best explains the formation of a covalent bond?

Accepted Answer

Atoms share electrons to complete their outer shells.

Question 11

Which equation represents the formation of bicarbonate ions that reduces carbonate available for coral skeletons?

Accepted Answer

$$H^+ + CO_3$^{2-} \rightarrow $$HCO_3$$^-$$

Question 12

Which of the following is true about isotopes?

Accepted Answer

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

Question 13

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

Accepted Answer

Cohesion due to hydrogen bonding

Question 14

Which of the following best describes the pH scale?

Accepted Answer

A scale that describes how acidic or basic a solution is

Question 15

Which of the following is a real-world consequence of ocean acidification?

Accepted Answer

Reduced rate of calcification in coral reefs

Question 16

Which of the following is NOT a life-supporting property of water?

Accepted Answer

Water is a poor solvent for polar molecules.

Question 17

Which of the following best describes an ionic compound?

Accepted Answer

A substance consisting of ions held together by opposite charges

Question 18

Which of the following is a correct statement about chemical reactions?

Accepted Answer

Chemical reactions rearrange matter by breaking and forming chemical bonds.

Question 19

Which of the following best explains why humidity makes hot weather feel worse?

Accepted Answer

High humidity slows evaporative cooling because sweat does not evaporate easily.

Question 20

Which of the following is true about the atomic mass of an element?

Accepted Answer

It is approximately equal to the sum of protons and neutrons.

The Chemical Basis of Life: Elements, Atoms, and Compounds

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