$$1 \times 10$$^{-9}$$\ \mathrm{M}$$

Question 1

Which of the following statements best explains why water is considered a versatile solvent in biological systems?

Accepted Answer

Water molecules are polar, allowing them to interact with and dissolve many ionic and polar substances.

Question 2

A solution has a pH of 4. Which of the following statements is true about this solution?

Accepted Answer

It is acidic and has a higher concentration of H$$^+$$ ions than OH$$^-$$ ions.

Question 3

Which type of chemical bond is formed by the sharing of two pairs of electrons between atoms?

Accepted Answer

Double covalent bond

Question 4

If the atomic number of an element is 8 and its atomic weight is 16, how many neutrons does a neutral atom of this element have?

Accepted Answer

8

Question 5

Which property of water allows it to resist changes in temperature, helping organisms maintain homeostasis?

Accepted Answer

High specific heat

Question 6

A buffer solution is important in biological systems because it:

Accepted Answer

Maintains a constant pH by accepting or donating H$$^+$$ ions.

Question 7

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 8

What is the molarity of a solution containing 0.5 moles of NaCl in 1 liter of water?

Accepted Answer

$$0.5\ \mathrm{M}$$

Question 9

Which of the following is true about hydrogen bonds?

Accepted Answer

They are weak attractive forces between polar molecules.

Question 10

A molecule of water (H$$_2O) $$can dissociate into which ions?

Accepted Answer

H$$^+$$ and OH$$^-$$

Question 11

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally, resulting in partial charges.

Question 12

If a solution has a pH of 9, what is the concentration of H$$^+$$ ions in the solution?

Accepted Answer

$$1 	imes 10$$^{-9}$$\ \mathrm{M}$$

Question 13

Which of the following is a consequence of water's high heat of vaporization?

Accepted Answer

Evaporation of water leads to cooling of surfaces.

Question 14

Which statement correctly describes the difference between a compound and a mixture?

Accepted Answer

A compound is composed of two or more elements in a fixed ratio, while a mixture is composed of elements or compounds in a variable ratio.

Question 15

Which of the following best explains why ice floats on water?

Accepted Answer

Ice is less dense than liquid water because water expands when it freezes.

Question 16

A molecule has a region with a partial positive charge and a region with a partial negative charge. What type of bond is most likely present?

Accepted Answer

Polar covalent bond

Question 17

Which of the following is the correct formula for calculating the molecular weight of a molecule?

Accepted Answer

$$	ext{Molecular weight} = \sum 	ext{atomic masses of all atoms in the molecule}$$

Question 18

Which of the following best describes a cation?

Accepted Answer

A positively charged atom or molecule

Question 19

A student adds 1 mole of glucose (C$$_6H$_{12}O$_6) to $$enough water to make 1 liter of solution. What is the molarity of the solution?

Accepted Answer

$$1\ \mathrm{M}$$

Question 20

Which of the following is a real-life example of a buffer system in the human body?

Accepted Answer

Bicarbonate buffer system

Atoms, Molecules, and Life: Foundations of Chemistry in Biology

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