Question 1

Which type of bond is primarily responsible for holding one water molecule to another in liquid water?

Accepted Answer

Hydrogen bond

Question 2

Why does ice float on liquid water?

Accepted Answer

Because hydrogen bonds keep water molecules in ice farther apart, making ice less dense than liquid water

Question 3

Which property of water is most directly responsible for the ability of sweating to lower body temperature in mammals?

Accepted Answer

Evaporative cooling due to hydrogen bonding

Question 4

A solution has a pH of 5. What is the hydrogen ion concentration $$[H^+] in $$this solution?

Accepted Answer

$$1 	imes 10$$^{-5}$$ M

Question 5

If the pH of a solution changes from 6 to 8, how does the hydrogen ion concentration change?

Accepted Answer

It decreases by 100 times

Question 6

Which of the following best explains why water is an excellent solvent for ionic compounds?

Accepted Answer

Water molecules are polar and form hydration shells around ions

Question 7

Which of the following equations correctly relates pH and hydrogen ion concentration?

Accepted Answer

$$\mathrm{pH} = -\log_{10} [H^+]$$

Question 8

Which of the following is a real-life example of the importance of molecular shape in biology?

Accepted Answer

The ability of morphine to bind to endorphin receptors due to similar shape

Question 9

Which of the following statements about catalysts is correct?

Accepted Answer

Catalysts increase the rate of a reaction without being consumed

Question 10

A chemical reaction is written as $$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2. $$Which of the following is true?

Accepted Answer

The reactants are $$6CO_2$$ and $$6H_2O$$; the products are $$C_6H_{12}O_6$ and 6O_2$

Question 11

Which property of water allows it to climb up a plant stem against gravity?

Accepted Answer

Cohesion and adhesion due to hydrogen bonding

Question 12

What is the relationship between $$[H^+]$$ and $$[OH^-] in a $$neutral aqueous solution at 25°C?

Accepted Answer

$$[H^+] = [OH^-]$$

Question 13

Which of the following best describes the effect of a catalyst on a chemical reaction?

Accepted Answer

It decreases the activation energy required for the reaction

Question 14

Which bond type holds the atoms together within a single water molecule?

Accepted Answer

Polar covalent bond

Question 15

A solution has a pH of 3. Compared to a solution with pH 6, how many times greater is the hydrogen ion concentration?

Accepted Answer

1000 times greater

Question 16

Which of the following is NOT an emergent property of water that contributes to Earth's suitability for life?

Accepted Answer

High density as a solid

Question 17

Which of the following best explains why molecules with similar shapes can have similar biological effects?

Accepted Answer

They can bind to the same biological receptors

Question 18

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

Accepted Answer

Chemical reactions involve both the making and breaking of chemical bonds

Question 19

If a solution has $$[H^+] = 1 	imes 10$$^{-9}$$ M, what is its pH?

Accepted Answer

pH = 9

Question 20

Which of the following best describes the role of enzymes in biological systems?

Accepted Answer

They act as catalysts to speed up chemical reactions without being consumed

The Chemical Context of Life: Water, Chemical Bonds, and Reactions

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