Question 1

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

Accepted Answer

Water molecules form hydrogen bonds with polar and charged molecules, allowing them to dissolve easily.

Question 2

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

Accepted Answer

Atomic number: 7, Mass number: 14

Question 3

Which of the following statements about covalent bonds is correct?

Accepted Answer

Covalent bonds form when two atoms share unpaired valence electrons.

Question 4

Which property of water is primarily responsible for the formation of a meniscus in a glass tube?

Accepted Answer

Adhesion between water molecules and glass

Question 5

If the concentration of hydronium ions in a solution is $$1 	imes 10$$^{-5}$$ M, what is the pH of the solution?

Accepted Answer

$$pH = 5$$

Question 6

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

Accepted Answer

Ice has a relatively open crystal structure stabilized by hydrogen bonds, making it less dense than liquid water.

Question 7

Which of the following is a correct statement about the relationship between potential energy and chemical bonds?

Accepted Answer

Long, weak bonds have higher potential energy than short, strong bonds.

Question 8

A molecule of methane ($$CH_4) $$contains which type of covalent bonds?

Accepted Answer

Four nonpolar covalent bonds

Question 9

Which of the following best explains why carbon is considered the most versatile atom in organic chemistry?

Accepted Answer

Carbon can form up to four covalent bonds, allowing for a variety of molecular shapes and combinations.

Question 10

Which of the following scenarios would most likely result in a spontaneous chemical reaction according to the laws of thermodynamics?

Accepted Answer

The products have lower potential energy and higher entropy than the reactants.

Question 11

Which of the following best describes the difference between an ion and an isotope?

Accepted Answer

An ion has a different number of electrons, while an isotope has a different number of neutrons.

Question 12

Which of the following is a real-life example of a buffer system in biology, and what is its primary function?

Accepted Answer

The bicarbonate buffer system in blood; it helps maintain a stable pH.

Question 13

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 14

Which of the following best explains why water has a high specific heat capacity?

Accepted Answer

Hydrogen bonds between water molecules require a large amount of energy to break.

Question 15

Which of the following is true regarding acids and bases in aqueous solutions?

Accepted Answer

Acids increase the concentration of protons ($$[H^+]$$), while bases decrease it.

Question 16

Which of the following best describes the role of entropy in determining whether a chemical reaction is spontaneous?

Accepted Answer

A reaction is more likely to be spontaneous if it results in increased entropy.

Question 17

Which of the following is a correct statement about hydrogen bonds?

Accepted Answer

Hydrogen bonds are weak electrical attractions between the partial positive charge on a hydrogen atom and the partial negative charge on another atom.

Question 18

Which of the following best explains why nonpolar molecules do not dissolve in water?

Accepted Answer

Nonpolar molecules cannot form hydrogen bonds with water and are excluded from the aqueous environment.

Question 19

Which of the following is a correct application of the first law of thermodynamics to biological systems?

Accepted Answer

Energy is conserved in biological systems; it can be transferred or transformed but not created or destroyed.

Question 20

Which of the following best describes the difference between kinetic and potential energy in biological systems?

Accepted Answer

Potential energy is stored in chemical bonds, while kinetic energy is the energy of molecular motion.

Water and Carbon: The Chemical Basis of Life (BLG143 Chapter 2 Study Notes)

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