Biology Notes 1,2 - 3,4,

What happens to hydrogen bonds in water as it cools?

• They break apart completely.

• More hydrogen bonds form, releasing heat.

• They remain unchanged.

• They become stronger but do not release heat.

What is the primary reason water has a high boiling point?

• It has a low density.

• It has a high heat of evaporation due to hydrogen bonds.

• It evaporates easily.

• It contains dissolved salts.

What occurs when vapor condenses to form liquid water?

• Heat is absorbed.

• Heat is released.

• No heat change occurs.

• Water freezes.

At what temperature is water densest?

• 0 °C

• 4 °C

• 100 °C

• 32 °C

Why does ice float on water?

• Ice is denser than water.

• Ice has a stable structure with fewer molecules than water.

• Ice is made of different molecules than water.

• Ice is warmer than water.

What is the effect of water's high dielectric constant?

• It makes water a poor solvent.

• It allows water to dissolve ionic compounds effectively.

• It increases the boiling point of water.

• It decreases the density of water.

What happens to ions in a salt crystal when placed in water?

• They remain intact and do not dissolve.

• They are surrounded by water molecules and dissolve.

• They form new bonds with water.

• They evaporate into the air.

Which type of molecules can form hydrogen bonds with water?

• Nonpolar molecules

• Hydrophobic molecules

• Polar molecules

• Ionic molecules

What characterizes hydrophobic molecules?

• They dissolve easily in water.

• They have charged regions.

• They do not interact with water.

• They form hydrogen bonds with water.

What is the result of water dissociating into H+ and OH- ions?

• It becomes a solid.

• It creates an acidic solution.

• It releases free protons into solution.

• It increases the temperature of the water.