Chapter 2: The Chemistry of Life

Which of the following properties of water enables it to move from the roots to the leaves of plants?

• Water expands as it freezes.
• Water is an excellent solvent.
• Water exhibits cohesive behavior.
• Water moderates temperature.

Large bodies of water do not quickly fluctuate in temperature. Why?

• Water is a solvent.
• Water has a high heat capacity.
• Water acts as a buffer.
• Water is non-polar.

What two elements make up water?

• Helium and oxygen
• Hydrogen and oxygen
• helium and carbon
• oxygen and carbon

What word describes when water is attracted to other substances?

• cohesion
• adhesion
• capillary action
• surface tension

Why can water have no net charge but have slight charges in different parts of the molecule?

• The oxygen end is slightly negative and the hydrogen end is slightly positive
• The hydrogen end is slightly negative and the oxygen end is slightly positive
• The hydrogen and oxygen ends change in polarity
• Because it is hydrophobic

Attractions between water molecules are called

• Covalent bonds
• Ionic bonds
• Polar bonds
• Hydrogen bonds

Why does ice float?

• As water freezes, it expands and its density decreases.
• As water freezes, it takes up more hydrogen from the atmosphere, causing it to have a greater buoyancy.
• As water freezes, air becomes trapped between the hydrogen bonds of water molecules.
• As water freezes, it takes up more oxygen from the atmosphere, causing it to have a greater buoyancy.

Water is polar because...

• The unequal sharing of electrons gives the water molecule a slight negative charge near its oxygen atom and a slight positive charge near its hydrogen atoms.
• The molecule has two poles, at which the it is colder than other regions of the molecule.
• The unequal sharing of electrons gives the water molecule a slight negative charge near its hydrogen atoms and a slight positive charge near its oxygen atom.
• The water molecule is neutral.

tendency of molecules of the same kind to stick to one another

• cohesion
• adhesion
• solution
• polar molecule

Which end of the water molecule has a slightly positive charge?

• the oxygen end
• the hydrogen end
• both ends are slightly positive
• neither end is positive