Question 1

Which of the following best describes a trace element in living organisms?

Accepted Answer

An element required in minute quantities but essential for life

Question 2

A carbon atom has 6 protons, 6 neutrons, and 6 electrons. What is its atomic number and mass number?

Accepted Answer

Atomic number: 6, Mass number: 12

Question 3

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have different numbers of neutrons

Question 4

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 5

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

Accepted Answer

Water molecules form hydrogen bonds with ions, surrounding and separating them

Question 6

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

Accepted Answer

The carbonic acid-bicarbonate system in blood

Question 7

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

Accepted Answer

$$5$$

Question 8

Which property of water allows insects such as water striders to walk on its surface?

Accepted Answer

Cohesion due to hydrogen bonding

Question 9

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of electron pairs between atoms

Question 10

A molecule of methane ($$CH_4) $$has what type of covalent bonds between carbon and hydrogen?

Accepted Answer

Nonpolar covalent bonds

Question 11

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

Accepted Answer

Hydrogen bonds in ice keep water molecules farther apart

Question 12

Which of the following is NOT a unique property of water that supports life on Earth?

Accepted Answer

Low specific heat

Question 13

If a solution changes from pH 6 to pH 4, how does the hydrogen ion concentration change?

Accepted Answer

It increases by 100 times

Question 14

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom

Question 15

Which of the following best explains why salt (NaCl) dissolves easily in water?

Accepted Answer

Water molecules are polar and stabilize the separated Na$$^+$$ and Cl$$^-$$ ions

Question 16

Which of the following is an example of a hydrophobic substance?

Accepted Answer

Olive oil

Question 17

Which of the following best describes the difference between an ionic bond and a covalent bond?

Accepted Answer

Ionic bonds involve transferring electrons; covalent bonds involve sharing electrons

Question 18

A patient is diagnosed with acidosis, meaning their blood pH is below normal. Which of the following could help restore their blood pH to normal?

Accepted Answer

Adding a buffer that can accept excess hydrogen ions

Question 19

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

Accepted Answer

Sweat absorbs heat as it evaporates due to water's high heat of vaporization

Question 20

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

Accepted Answer

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

Fundamental Chemistry for Biology: Elements, Atoms, Bonds, and Water

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