Click on the box which shows the correct answer.

1. The half-life of a radioactive material is

   1.   ?    Half the time it took the material to form in the Earth's crust
   2.   ?    The time it takes for the material to lose half of its radioactivity.
   3.   ?    The time it takes for the radioactive material to give out half its radioactivity
   4.   ?    The time it takes for the material before it must be removed from the power plant and safely stored

2. The longer the half-life of a radioactive material

   1.   ?    the more of it is needed to produce energy in a nuclear power station
   2.   ?    the more expensive it is to buy.
   3.   ?    the less time it takes for the material to be stored before it becomes safe.
   4.   ?    the more time it takes for the material to be stored before it becomes safe.

3. Alcohol for use as a fuel can be obtained from

   1.   ?    cow dung
   2.   ?    tree bark
   3.   ?    sugar
   4.   ?    compost

4. The process which converts sugar into alcohol is known as

   1.   ?    Fermentation
   2.   ?    Condensation
   3.   ?    Fractional distillation
   4.   ?    Evaporation

5. Extracting energy by pumping cold water down into hot rocks and using the steam produced to make electricity is called

   1.   ?    Seismic energy
   2.   ?    Hydro-electric energy
   3.   ?    Geological energy
   4.   ?    Geothermal energy