Solutions review

What word describes when water is attracted to other substances?

• cohesion
• adhesion
• capillary action
• surface tension

Attractions between the negative Oxygen atom of one water molecule and the positive Hydrogen atom of another water molecule 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.

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

Water is a universal solvent because it...

• It can be found anywhere
• It freezes when it gets cold
• floats when frozen
• Dissolves most substances

 Small insects can walk across the surface of calm water. Their feet push the surface of the water down slightly, somewhat like a person walking across a trampoline, but they do not break the surface. What is the best explanation for why this happens?

• The insects are light enough so that they do not break the hydrogen bonds holding the water molecules together
• The insects actually use their wings to hover slightly above the water's surface and they only skim it with their feet
• The insects' feet are non-polar, so they are repelled by the polar water molecules and are pushed away from the water's surface
• The insects are small enough to see the individual water molecules, so they are able to step carefully from one molecule to the next

 Many fish and aquatic plants can survive a cold winter because the layer of ice that forms at the top of the lake insulates the water below and prevents the lake from freezing solid. What unique property of water contributes to this effect? 

• Water absorbs heat when it evaporates and forms a gas 
•  Water expands and becomes less dense when it freezes.
• Water molecules completely separate into ions in solutions.
•  Water forms hydrogen bonds with ions and other polar substances. 

True or false water is a polar molecule? 

• True 
• False 

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

Why is water so good at dissolving so many substances?

• it is polar

• it is less dense as a solid

• cohesion

• adhesion