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

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

Question 1

Which of the following best explains why water is an excellent solvent for many biological molecules?

Accepted Answer

Water is highly polar, allowing it to form hydrogen bonds with charged and polar molecules.

Question 2

A researcher is studying a molecule with the formula $$C_6H_{12}O_6$. Which type of bond is most likely to be found between the carbon and hydrogen atoms in this molecule?

Accepted Answer

Nonpolar covalent bonds

Question 3

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 4

Which property of water is primarily responsible for the phenomenon of surface tension?

Accepted Answer

Cohesion between water molecules due to hydrogen bonding

Question 5

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}$$ \ 	ext{M}$$

Question 6

Which of the following best describes the difference between a polar covalent bond and a nonpolar covalent bond?

Accepted Answer

Polar covalent bonds involve unequal sharing of electrons due to differences in electronegativity, while nonpolar covalent bonds involve equal sharing.

Question 7

Which of the following functional groups acts as a base by attracting a proton?

Accepted Answer

Amino group

Question 8

Why does ice float on liquid water?

Accepted Answer

Ice is less dense than liquid water because its hydrogen bonds form an open crystal structure.

Question 9

Which of the following best describes a spontaneous chemical reaction?

Accepted Answer

A reaction that proceeds on its own, resulting in products with lower potential energy and/or higher entropy.

Question 10

Which of the following is a correct statement about the first law of thermodynamics?

Accepted Answer

Energy can be transferred or transformed but cannot be created or destroyed.

Question 11

A scientist adds a base to a solution. What effect does this have on the concentration of hydronium ions $$[H_3O^+]$$?

Accepted Answer

It decreases $$[H_3O^+] by $$accepting protons.

Question 12

Which of the following best explains why sweating is an effective way to cool the human body?

Accepted Answer

Water has a high heat of vaporization, so it absorbs a lot of energy as it evaporates.

Question 13

Which of the following is true about the valence of an atom?

Accepted Answer

It is the number of unpaired electrons in the outermost shell.

Question 14

Which of the following best describes the process of hydrolysis in biological systems?

Accepted Answer

Hydrolysis breaks a polymer into monomers by adding a water molecule.

Question 15

Which of the following statements about chemical evolution is supported by the Miller-Urey experiment?

Accepted Answer

Simple molecules with high free energy can form complex organic molecules when exposed to energy.

Question 16

Which of the following is a property of hydrophobic molecules?

Accepted Answer

They cluster together in water due to hydrophobic interactions.

Question 17

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

Accepted Answer

Buffers minimize changes in pH by accepting or donating protons.

Question 18

Which of the following statements about carbon is correct?

Accepted Answer

Carbon forms four covalent bonds, allowing for a variety of molecular shapes.

Question 19

Which of the following best explains why the geometry of a water molecule is bent rather than linear?

Accepted Answer

The two unshared pairs of electrons on the oxygen atom repel the hydrogen atoms, resulting in a bent shape.

Water and Carbon: The Chemical Basis of Life (Chapter 2 Study Notes)

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