Using materials (chemistry only): Practice Questions

• a.

  Only water must be present.

• b.

  Iron must be in a vacuum with salt.

• c.

  Only air (oxygen) must be present.

• d.

  Both air and water must be present.

• a.

  Different sized atoms in the alloy distort the layers, making it more difficult for them to slide over each other.

• b.

  Alloys contain stronger metallic bonds than pure metals.

• c.

  Alloys have a higher density, which prevents the atoms from moving.

• d.

  The atoms in an alloy are arranged in perfectly flat layers that are locked in place.

• a.

  It is the temperature at which the yield of ammonia is at its absolute maximum.

• b.

  It is the temperature required to make the iron catalyst turn into a liquid.

• c.

  It is a compromise between a high yield at low temperatures and a high rate of reaction at high temperatures.

• d.

  Higher temperatures would decrease the rate of the reverse reaction too much.

• a.

  Thermosetting polymers melt when heated, while thermosoftening polymers do not melt.

• b.

  Both types of polymers melt at exactly the same temperature.

• c.

  Thermosoftening polymers contain cross-links that prevent melting.

• d.

  Thermosoftening polymers melt when heated, while thermosetting polymers do not melt.

• a.

  82%

• b.

  50%

• c.

  75%

• d.

  18%

Write your answer out first, then check it against the worked solution.