31) An atom becomes an ion when:
A) it gains or : 1380705.
31) An atom becomes an ion when:
A) it gains or loses neutrons.
B) it forms a covalent bond.
C) it gains or loses electrons.
D) hydrogen ions are shared.
E) it gains or loses protons.
32) Sodium chloride (NaCl) crystals (table salt) form as a result of:
A) covalent bonding.
B) hydrogen bonding.
C) being chemically stable.
D) the attraction of oppositely charged particles for each other.
33) Hydrogen bonds are very important in the functional shape of:
D) nucleic acids.
E) proteins and nucleic acids.
34) In a bottle of water, hydrogen bonding occurs between the hydrogen of one atom and a/an:
A) hydrogen atom in the same molecule.
B) oxygen atom in a different molecule.
C) oxygen atom in the same water molecule.
D) hydrogen atom in a different molecule.
35) In hydrogen bonding, hydrogen nearly always pairs with:
A) another hydrogen.
C) oxygen or nitrogen.
D) sodium or chlorine.
36) In what ways are hydrogen bonds and ionic bonds similar?
A) Both are based on attraction between atoms that carry differences in electrical charge.
B) Both involve an even sharing of electrons between atoms.
C) Both are based on attraction between two atoms where each carries a positive charge.
D) Both are based on repulsion between atoms that carry differences in electrical charge.
E) Both are based on attraction between two atoms where each carries a negative charge.
37) Molecules of water stick to each other because:
A) hydrogen bonds form between the hydrogen atom of one molecule and the oxygen atom of another molecule.
B) water molecules are nonpolar, and nonpolar molecules stick together.
C) hydrogen bonds form between the hydrogen atom of one molecule and a hydrogen atom of another molecule.
D) covalent bonds form between the hydrogen atom of one molecule and the oxygen atom of another molecule.
38) When sodium chloride dissolves in water, the sodium and chloride ions are pulled into solution by:
A) ionic bonds that form between the ions and the water molecules.
B) the attraction of the sodium ions to the negatively charged oxygen, and the attraction of the chloride ions to the two positively charged hydrogens of the water molecules.
C) the attraction of the sodium ions to the positively charged oxygen, and the attraction of the chloride ions to the two negatively charged hydrogens of the water molecules.
D) covalent bonds that form between the ions and the water molecules.
39) Hydrophobic molecules tend to be ________ by water.
40) You mix sugar in water and stir until it’s completely dissolved. In this system, the water is the ________, the sugar is the ________, and the end result is a ________.
A) solute; solution; solvent
B) solute; solvent; solution
C) solvent; solution; solute
D) solution; solvent; solute
E) solvent; solute; solution
41) You shake up a bottle of vinegar and oil dressing to mix it each time you use it. The reason you need to do this is that:
A) oil is hydrophobic and won’t dissolve in vinegar, so the oil and vinegar separate upon standing.
B) vinegar and oil are oppositely charged, and opposites attract.
C) fat molecules are too large to dissolve in water.
D) vinegar has an acidic pH and is neutralized when mixed with oil.
42) The high specific heat and surface tension of water are a result of:
A) ionic bonds.
B) covalent bonds within the water molecules.
C) the size of water molecules.
D) hydrogen bonding between water molecules.
E) covalent bonds between water molecules.
43) As an acid mixes in water:
A) the number of hydroxide ions will increase.
B) the number of hydrogen ions will increase.
C) the pH remains at 7.
D) it becomes buffered.
44) Buffering systems work to maintain pH within normal limits by:
A) adding hydrogen ions when conditions becomes too acidic.
B) adding hydroxide ions when conditions become too basic.
C) removing hydrogen ions when conditions become too acidic and adding hydrogen ions when conditions become too basic.
D) adding hydrogen ions when conditions become too acidic and removing hydrogen ions when conditions become too basic.