Q: If the concentration of $$[H^+] in a $$solution is $$1 \times 10$$^{-8}$$ M, what is the concentration of $$[OH^-]$$ at 25°C, given that $$[H^+][OH^-] = 1 \times $$10^{-14}$$?

$$[OH^-] = 1 \times 10$$^{-6}$$ M

Question 1

Which property of water is primarily responsible for the transport of water from the roots to the leaves in plants against gravity?

Accepted Answer

Its cohesive behavior due to hydrogen bonding

Question 2

Why does ice float on liquid water, and what is the biological significance of this property?

Accepted Answer

Hydrogen bonds in ice are more ordered, making it less dense than liquid water, allowing ice to float and insulate aquatic environments.

Question 3

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-5}$$ M. What is its pH?

Accepted Answer

$$pH = 5$$

Question 4

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, separating and dissolving them.

Question 5

If the concentration of $$[H^+] in a $$solution is $$1 	imes 10$$^{-8}$$ M, what is the concentration of $$[OH^-]$$ at 25°C, given that $$[H^+][OH^-] = 1 	imes $$10^{-14}$$?

Accepted Answer

$$[OH^-] = 1 	imes 10$$^{-6}$$ M

Question 6

A patient is suffering from acidosis (blood pH below 7.35). Which of the following buffer systems in the blood helps resist further decrease in pH?

Accepted Answer

The $$H_2CO_3 / $$HCO_3$$^-$$ buffer system, which can accept excess $$H^+$$ ions

Question 7

Which of the following scenarios best illustrates the concept of water's high specific heat in a real-world context?

Accepted Answer

A lake remains relatively cool during a hot summer day, moderating the temperature of the surrounding area.

Question 8

What would happen to the freezing point of water if salt is added, and why is this important for road safety in winter?

Accepted Answer

The freezing point decreases, preventing ice formation and making roads safer.

Question 9

Which of the following best describes a hydrophobic molecule and its behavior in water?

Accepted Answer

A molecule with nonpolar bonds that aggregates together in water, such as oils.

Question 10

Ocean acidification is a result of increased atmospheric $$CO_2. $$What is the chemical process that leads to a decrease in carbonate ion concentration in seawater?

Accepted Answer

$$CO_2$$ dissolves in seawater, forms carbonic acid, which releases $$H^+$$ ions that combine with carbonate ions to form bicarbonate.

Question 11

A biologist is studying a protein that dissolves in water. Which property of water allows large polar molecules like proteins to dissolve?

Accepted Answer

Water's ability to form hydrogen bonds with polar or ionic regions of the protein

Question 12

Which of the following statements about acids and bases is correct?

Accepted Answer

A base decreases the $$[H^+]$$ concentration in a solution.

Question 13

If a solution has a pH of 4, how many times more acidic is it than a solution with a pH of 7?

Accepted Answer

1,000 times

Question 14

Why is it important for the internal pH of most living cells to remain close to 7?

Accepted Answer

Because enzymes and biochemical reactions are highly sensitive to changes in pH, and deviations can disrupt cellular function.

Question 15

Which of the following best explains why water can moderate Earth's climate?

Accepted Answer

Water has a high specific heat, so it absorbs and releases large amounts of heat with little change in its own temperature.

Question 16

A student adds a strong acid to a buffered solution. What will happen to the pH of the solution compared to an unbuffered solution?

Accepted Answer

The pH will decrease only slightly, as the buffer minimizes changes in $$[H^+].$$

Question 17

Which of the following is a direct consequence of water's polarity?

Accepted Answer

Water molecules can form hydrogen bonds with each other and with other polar molecules.

Question 18

During dehydration, which of the following physiological changes is most likely to occur?

Accepted Answer

Drop in blood volume and pressure, leading to potential organ failure

Question 19

Which of the following best describes the relationship between water and cellular chemical reactions?

Accepted Answer

Water acts as a medium for hydrophilic molecules and pushes back on hydrophobic molecules, influencing processes like protein folding.

Water and Life: Properties, Importance, and Biological Roles

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