How many grams of water are made from the reaction of 16.0 grams of oxygen gas? Given the reaction: 2 H2 + O2⟶
⟶
2H2O

the answer is 0.42 is that is an option. this question provides no info

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

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.