The answer for this question is the smallest particle of matter.
Explanation:
According to Le Chatelier's principle, any disturbance caused in an equilibrium reaction will shift the equilibrium in a direction that will oppose the change.
As the given reaction is as follows.

(a) When increase the temperature of the reactants or system then equilibrium will shift in forward direction where there is less temperature. It is possible for an endothermic reaction.
Thus, formation of
will increase.
- (b) When we decrease the volume (at constant temperature) of given reaction mixture then it implies that there will be increase in pressure of the system. So, equilibrium will shift in a direction where there will be decrease in composition of gaseous phase. That is, in the backward direction reaction will shift.
Hence, formation of
will decrease with decrease in volume.
- When we increase the mount of
then equilibrium will shift in the direction of decrease in concentration that is, in the forward direction.
Thus, we can conclude that formation of
will increase then.
The compound that could serve as a reactant in the neutralization reaction is H2SO4
Explanation
Neutralization reaction occur between an acids and a base. H2SO4 ( sulfuric acid) is a strong acid. It can be neutralized by strong base such as NaOH ( sodium hydroxide)
Example of neutralization reaction is
2NaOH + H2SO4 → Na2SO4 + 2H2O