Q: A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

$$[H^+] = 1 \times 10$$^{-4}$$ M

Question 1

Which property of water allows ice to float on liquid water, and what is the underlying reason for this phenomenon?

Accepted Answer

Water is less dense as a solid than as a liquid; ice floats because the hydrogen bonds in ice hold water molecules farther apart.

Question 2

A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ M

Question 3

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

Accepted Answer

A buffer is a chemical or combination of chemicals that helps maintain a relatively constant pH by neutralizing acids and bases.

Question 4

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

Accepted Answer

Acids release hydrogen ions ($$H^+) in $$water, while bases release hydroxide ions ($$OH^-).$$

Question 5

A scientist adds a strong acid to a solution, causing the pH to drop from 7 to 3. By what factor has the hydrogen ion concentration increased?

Accepted Answer

By a factor of 10,000

Question 6

Which of the following is NOT a property of water that is important for life?

Accepted Answer

Water is more dense as a solid than as a liquid.

Question 7

Which of the following molecules is NOT a carbohydrate?

Accepted Answer

Glycine

Question 8

Which statement best describes the difference between saturated and unsaturated fatty acids?

Accepted Answer

Unsaturated fatty acids contain double bonds, making them liquid at room temperature, while saturated fatty acids do not contain double bonds and are solid at room temperature.

Question 9

Which of the following is an example of a disaccharide?

Accepted Answer

Sucrose

Question 10

Amino acids are the building blocks of proteins. Which of the following statements about amino acids is TRUE?

Accepted Answer

Amino acids contain the necessary information to fold into a 3-D structure.

Question 11

Which level of protein structure is defined by the sequence of amino acids in a polypeptide chain?

Accepted Answer

Primary structure

Question 12

Which of the following is a function of proteins in living organisms?

Accepted Answer

They act as enzymes to speed up chemical reactions.

Question 13

Which of the following is an essential amino acid that must be obtained from the diet?

Accepted Answer

Serine

Question 14

What is the result when an acid reacts with a base?

Accepted Answer

A salt and water are formed.

Question 15

Which of the following best describes the process of dissociation in water?

Accepted Answer

Water molecules break apart into ions, such as $$H^+$$ and $$OH^-.$$

Question 16

Which of the following statements about lipids is correct?

Accepted Answer

Lipids are used to store energy and support membranes in plants and animals.

Question 17

Which of the following is NOT a type of lipid?

Accepted Answer

Starch

Question 18

Which carbohydrate is found in plant cell walls and provides structural strength?

Accepted Answer

Cellulose

Question 19

Which of the following best explains why soaps can emulsify oils in water?

Accepted Answer

Soaps are amphiphilic molecules that have both hydrophobic and hydrophilic regions, allowing them to interact with both oil and water.

General Biology: Properties of Water, Acids & Bases, Biomolecules, and Lipids

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