Any fire extinguisher should put out a fire, that is unless the extinguisher is old and faulty.
Answer : The mathematical equation used when solving calorimetry problems is:

Explanation :
Calorimetry : It is determining the changes in the energy of a system by measuring the heat transferred with surroundings.
Formula used :

where,
c = specific heat capacity of calorimeter
m = mass of a substance
q = heat required
= change in temperature of substance
Independent atoms have high potential energy,and they are highly unstable.
And when they form bonds their potential energy decreases and they become stable.
Hence bonded atoms are stable and have relatively low potential energy than independent atoms.