BIO 1 Ch3 Exam Qs

A strong acid like HCl A) ionizes completely in an aqueous solution. B) increases the pH when added to an aqueous solution. C) reacts with strong bases to create a buffered solution. D) is a strong buffer at low pH. E) both ionizes completely in aqueous solutions and is a strong buffer at low pH.

A - ionizes completely in an aqueous solution

Hydrophobic substances such as vegetable oil are A) nonpolar substances that repel water molecules. B) nonpolar substances that have an attraction for water molecules. C) polar substances that repel water molecules. D) polar substances that have an affinity for water. E) charged molecules that hydrogen-bond with water molecules.

A - nonpolar substance that repel water molecule

Which of the following effects is produced by the high surface tension of water? A) Lakes don't freeze solid in winter, despite low temperatures. B) A water strider can walk across the surface of a small pond. C) Organisms resist temperature changes, although they give off heat due to chemical reactions. D) Evaporation of sweat from the skin helps to keep people from overheating. E) Water flows upward from the roots to the leaves in plants.

B - A water strider can walk across the surface if a small pond

The partial negative charge in a molecule of water occurs because A) the oxygen atom acquires an additional electron. B) the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus. C) the oxygen atom has two pairs of electrons in its valence shell that are not neutralized by hydrogen atoms. D) the oxygen atom forms hybrid orbitals that distribute electrons unequally around the oxygen nucleus. E) one of the hydrogen atoms donates an electron to the oxygen atom.

B - the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus.

The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called? A) a covalent bond B) a hydrogen bond C) an ionic bond D) a hydrophilic bond E) a van der Waals interaction

B) a hydrogen bond

Water molecules can form hydrogen bonds with _____. A) chloride ions B) compounds that have polar covalent bonds C) oxygen gas (O2) molecules D) oils

B) compounds that have polar covalent bonds

Which type of bond must be broken for water to vaporize? A) both polar covalent bonds and hydrogen bonds B) hydrogen bonds C) polar covalent bonds D) ionic bonds

B) hydrogen bonds

The bonds that are broken when water vaporizes are A) ionic bonds. B) hydrogen bonds between water molecules. C) covalent bonds between atoms within water molecules. D) polar covalent bonds. E) nonpolar covalent bonds.

B- hydrogen bonds between water molecules

Liquid water's high specific heat is mainly a consequence of the A) small size of the water molecules. B) high specific heat of oxygen and hydrogen atoms. C) absorption and release of heat when hydrogen bonds break and form. D) fact that water is a poor heat conductor. E) higher density of liquid water than solid water (ice).

C - absorption and release of heat when hydrogen bonds break and form

If a solution has a pH of 7, this means that A) there are no H⁺ ions in the water. B) this is a solution of pure water. C) the concentration of H⁺ ions in the water equals the concentration of OH⁻ ions in the water. D) this is a solution of pure water, and the concentration of H⁺ ions in the water is 10⁻⁷ M. E) this is a solution of pure water, and the concentration of H⁺ ions equals the concentration of OH⁻ ions in the water.

C - the concentration of H+ ions in the water equals the concentration of OH- ions in the water

Temperature usually increases when water condenses. Which behavior of water is most directly responsible for this phenomenon? A) the change in density when it condenses to form a liquid or solid B) reactions with other atmospheric compounds C) the release of heat by the formation of hydrogen bonds D) the release of heat by the breaking of hydrogen bonds E) the high surface tension of water

C - the release of heat by the formation of hydrogen bonds

Which of the following is a hydrophobic material? A) paper B) table salt C) wax D) sugar E) pasta

C - wax

A strong acid like HCl _____. A)reacts with strong bases to create a buffered solution B)is a strong buffer at low pH C) dissociates completely in an aqueous solution D) increases the pH when added to an aqueous solution

C) dissociates completely in an aqueous solution

Which of the following statements is true about buffer solutions? A) They fluctuate in pH when either acids or bases are added to them. B) They maintain a constant pH when acids are added to them but not when bases are added to them. C) They maintain a relatively constant pH when either acids or bases are added to them. D) They maintain a constant pH when bases are added to them but not when acids are added to them.

C) they maintain a relatively constant pH when either acids or bases are added to them

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by _____. A) ionic bonds B) nonpolar covalent bonds C) polar covalent bonds D) hydrogen bonds

D) polar covalent bonds

Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature? A) water's change in density when it condenses B) water's ability to dissolve molecules in the air C) the release of heat by the formation of hydrogen bonds D) the absorption of heat by the breaking of hydrogen bonds E) water's high surface tension

D- the absorption of heat by the breaking of hydrogen bonds

Buffers are substances that help resist shifts in pH by A) releasing H⁺ to a solution when acids are added. B) donating H⁺ to a solution when bases are added. C) releasing OH⁻ to a solution when bases are added. D) accepting H⁺ from a solution when acids are added. E) both donating H⁺ to a solution when bases are added, and accepting H⁺ when acids are added.

E - both donating H+ to a solution when bases are added, and accepting H+ when acids are added