Question 1

Which of the following best explains why water is an excellent solvent for ionic compounds?

Accepted Answer

Water molecules are polar, allowing them to surround and stabilize both cations and anions through hydrogen bonding and electrostatic interactions.

Question 2

A neutral atom of phosphorus has an atomic number of 15 and a mass number of 31. How many neutrons does it have?

Accepted Answer

$$31 - 15 = 16$$ neutrons

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 of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of electron pairs between atoms.

Question 5

A radioactive isotope of carbon, $$^{14}C$$, has a half-life of 5,730 years. If a sample originally contains 100 grams of $$^{14}C$$, how much will remain after 11,460 years?

Accepted Answer

25 grams

Question 6

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

Accepted Answer

Cohesion between water molecules due to hydrogen bonding

Question 7

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

Accepted Answer

Hydrogen bonds in ice keep water molecules farther apart, making ice less dense than liquid water.

Question 8

Which of the following is an example of a trace element that is essential for human life?

Accepted Answer

Iron (Fe)

Question 9

A solution has a hydrogen ion concentration of $$[H^+] = 1 	imes 10$$^{-5}$$ M. What is the pH of this solution?

Accepted Answer

$$pH = 5$$

Question 10

Which of the following best describes a buffer in a biological system?

Accepted Answer

A substance that minimizes changes in pH by accepting or donating hydrogen ions.

Question 11

Which of the following best explains why water has a high specific heat compared to other substances?

Accepted Answer

Hydrogen bonds between water molecules absorb heat when they break and release heat when they form.

Question 12

Which of the following is a correct statement about the relationship between atomic number and mass number?

Accepted Answer

Atomic number is the number of protons; mass number is the sum of protons and neutrons.

Question 13

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

Accepted Answer

A polar covalent bond involves unequal sharing of electrons, while a nonpolar covalent bond involves equal sharing.

Question 14

Which of the following best explains why sweating helps cool the human body?

Accepted Answer

Evaporation of water from the skin absorbs heat energy due to water's high heat of vaporization.

Question 15

Which of the following is a real-world example of an ionic bond?

Accepted Answer

The bond between sodium and chlorine in table salt ($$NaCl)$$

Question 16

Which of the following best describes the effect of adding a strong acid to a buffered solution?

Accepted Answer

The pH will decrease slightly, but the buffer will minimize the change.

Question 17

Which of the following is the best explanation for why oil does not dissolve in water?

Accepted Answer

Oil molecules are nonpolar and cannot form hydrogen bonds with water.

Question 18

A solution has a hydroxide ion concentration of $$[OH^-] = 1 	imes 10$$^{-9}$$ M. What is the pH of this solution?

Accepted Answer

$$pH = 5$$

Question 19

Which of the following best describes the relationship between electronegativity and bond polarity?

Accepted Answer

A greater difference in electronegativity between two atoms results in a more polar bond.

Question 20

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

Accepted Answer

Hydrogen bonds form between the hydrogen atom of one water molecule and the oxygen atom of another water molecule.

Fundamental Chemistry Concepts in General Biology

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