Ch. 2 Review Questions - Biology for AP® Courses | OpenStax (2024)

What is the term for atoms of the same element that vary in the number of neutrons in their nuclei?

1. ions

2. isotopes

3. isobars

4. neutral atoms

Potassium has an atomic number of 19. What is its electron configuration?

1. Shells 1 and 2 are full, and shell 3 has nine electrons.

2. Shells 1, 2, and 3 are full, and shell 4 has three electrons.

3. Shells 1, 2, and 3 are full, and shell 4 has one electron.

4. Shells 1, 2, and 3 are full, and no other electrons are present.

Which type of bond exemplifies a weak chemical bond?

1. covalent bonds in solution

2. hydrogen bonds in solution

3. ionic bonds in solids

4. nonpolar covalent bonds in solids

Which of the following statements is false?

1. Electrons are unequally shared in polar covalent bonds.

2. Electrons are equally shared in nonpolar covalent bonds.

3. Hydrogen bonds are weak bonds based on electrostatic forces.

4. In solution, ionic bonds are generally stronger than covalent bonds.

If xenon has an atomic number of $54$ and a mass number of $108$, how many neutrons does it have?

1. $27$

2. $54$

3. $100$

4. $108$

What forms ionic bonds?

1. atoms that share electrons equally

2. atoms that share electrons unequally

3. ions with similar charges

4. ions with opposite charges

1. In NH₃, the nitrogen atom carries a partial positive charge and the hydrogen atoms acquire a partial negative charge.

2. In H₂O, the hydrogen atoms acquire a partial negative charge, and the oxygen atom carries a partial positive charge.

3. In aqueous HCl, the hydrogen atom carries a partial positive charge, and the chlorine atom carries a partial negative charge.

4. In LiF, the lithium atom carries a positive charge, and the fluorine atom carries a negative charge.

Which of the following statements is not true?

1. Water is polar.

2. Water can stabilize the temperature of nearby air.

3. Water is essential for life.

4. Water is the most abundant molecule in the Earth’s atmosphere.

Explain why the bonds within a water molecule are described as polar covalent bonds.

1. Hydrogen is more electronegative than oxygen, generating a partial negative charge near the hydrogen atom.

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2. Hydrogen is more electronegative than oxygen, generating a partial positive charge near the hydrogen atom.

3. Oxygen is more electronegative than hydrogen, generating a partial negative charge near the oxygen atoms.

4. Oxygen is more electronegative than hydrogen, generating a partial positive charge near the oxygen atoms.

What happens to the pH of a solution when acids are added?

1. The pH of the solution decreases.

2. The pH of the solution increases.

3. The pH of the solution increases and then decreases.

4. The pH of the solution stays the same.

Which of the following statements is true?

1. Acids and bases cannot mix together.

2. Acids and bases can neutralize each other.

3. Acids, not bases, can change the pH of a solution.

4. Acids donate hydroxide ions (${\text{OH}}^{-}$); bases donate hydrogen ions (${\text{H}}^{+}$).

Define water’s property of adhesion.

1. a force that allows surface water molecules to escape and vaporize

2. the attraction between water molecules and other molecules

3. the intermolecular force between water molecules

4. the force that keeps particles dispersed in water

How are excess hydrogen ions balanced in a solution?

1. acid

2. base

3. donator

4. isotope

What is the maximum number of atoms or molecules a single carbon atom can bond with?

1. 4

2. 1

3. 6

4. 2

Which of the following statements is true?

1. Molecules with the formulas ${\text{CH}}_3{\text{CH}}_2\text{OH}$ and ${\text{C}}_3{\text{H}}_6{\text{O}}_2$ could be structural isomers.

2. Cis-trans isomers are arranged about a single bond.

3. To be enantiomers, a pair of molecules must have at least three different atoms or groups connected to a central carbon, but arranged differently.

4. To be enantiomers, a pair of molecules must have four different atoms or groups connected to a central carbon, but arranged differently.

Which of the following is least likely to bond with carbon as a functional group in biological systems?

1. carbonyl

2. hydroxyl

3. phosphate

4. sodium

Which of the following functional groups is the least polar?

1. carbonyl

2. hydroxyl

3. methyl

4. sulfhydryl

What are enantiomers?

1. hydrocarbons consisting of closed rings of carbon atoms

2. structural isomers differing in placement of atoms along a carbon-carbon double bond

3. molecules sharing the same chemical bonds but are mirror images of each other

4. molecules with the same chemical formula but different placement of their chemical bonds