The empirical formula for a compound is CH2. Its
molar mass is 140.1 g/mol. What is its molecular
formula?

a basic emergency supply kit could include the following recommended items: water - one gallon of water per person per day for at least three days, for drinking and sanitation. food - at least a three-day supply of non-perishable food. battery-powered or hand crank radio and a noaa weather radio with tone alert.

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.