Which of these is an example of an experiment? Add different kinds of soil to three potted plants.
Beach erosion increased during the last winter storm.
Temperature changes may be due to wind patterns.
Wonder why some layers of rocks contain fossils.

Ithink this is what you meant. the temperature at which a liquid begins to boil is called the boiling point. the boiling point of water is 212°f or 100°c.  and at that point will start to turn into steam (gas)

Qand k are only the same when the forward rate of the reaction has reached zero.

Ithink ahopefully im correct 

Answer

it is the minimum amount of material needed to sustain a fission reaction.

explanation

critical mass is the minimum amount of fissionable material that must be assembled for a sustained fission reaction to take place. although two to three neutrons are produced for every fission, not all of these neutrons are available for continuing the fission reaction. if the conditions are such that the neutrons are lost at a faster rate than they are formed by fission, the chain reaction will not be self-sustaining.   at the point where the chain reaction can become self-sustaining, this is referred to as critical mass.