Question 1

Which of the following best describes how radioactive isotopes differ from nonradioactive isotopes of the same element?

Accepted Answer

Radioactive isotopes have a different number of neutrons, making their nuclei unstable and prone to decay.

Question 2

Which subatomic particle determines the atomic number of an element?

Accepted Answer

Proton

Question 3

A neutral atom of phosphorus (atomic number 15) has how many electrons?

Accepted Answer

15

Question 4

Which of the following statements about electron shells is correct?

Accepted Answer

The third shell can hold up to 16 electrons.

Question 5

What type of bond is formed when one atom donates an electron to another atom, resulting in oppositely charged ions that attract each other?

Accepted Answer

Ionic bond

Question 6

Which of the following best explains why water is a good solvent for ionic compounds like NaCl?

Accepted Answer

Water molecules are polar, so their positive and negative ends attract and separate the ions.

Question 7

Which property of water allows it to move upward through the vessels of a plant against gravity?

Accepted Answer

Cohesion and adhesion

Question 8

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

Accepted Answer

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

Question 9

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

Accepted Answer

A buffer maintains pH by accepting or releasing H$$^+$$ ions in response to changes in concentration.

Question 10

Which of the following is a real-life example of hydrogen bonding?

Accepted Answer

The attraction between water molecules that gives water its surface tension.

Question 11

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

Accepted Answer

Ice is less dense than liquid water because its molecules are held farther apart by hydrogen bonds.

Question 12

Which of the following molecules would be least likely to dissolve in water?

Accepted Answer

Olive oil

Question 13

A patient is given a radioactive isotope for a medical scan. Which property of the isotope makes it useful for this purpose?

Accepted Answer

It emits energy or particles as it decays, which can be detected.

Question 14

Which of the following best describes a polar covalent bond?

Accepted Answer

Electrons are shared unequally, resulting in partial charges on the atoms.

Question 15

Which of the following equations correctly represents the dissociation of water into ions?

Accepted Answer

$$ \mathrm{H_2O} \rightarrow \mathrm{H^+} + \mathrm{OH^-} $$

Question 16

A solution is made by dissolving sodium hydroxide (NaOH) in water. What effect does this have on the pH of the solution?

Accepted Answer

The pH increases, making the solution more basic.

Question 17

Which of the following best explains why sweating cools the human body?

Accepted Answer

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

Question 18

Which of the following is true about the mass number of an atom?

Accepted Answer

It is the sum of the number of protons and neutrons.

Question 19

Which of the following best describes the role of antioxidants in the human body?

Accepted Answer

Antioxidants donate electrons to free radicals, preventing them from damaging other molecules.

Question 20

Which of the following is a correct statement about noble gases such as helium and argon?

Accepted Answer

They are chemically inert because their outermost electron shells are completely full.

Atoms, Molecules, and Life: Foundations of Biological Chemistry

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