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.
Fluorine has 9 protons and 9 electrons
Iodine has 53 protons and 53 electrons
Answer is (4) - Pb.
According to the reactivity series of elements
- the elements which are above the hydrogen are more reactive than hydrogen.
- the elements which are below the hydrogen are less reactive than hydrogen.
Among the given choices, only Pb is placed above the hydrogen in the reactivity series and rest are below the hydrogen.
Hence, Pb is more active than hydrogen.
Sources of pollution can be natural, but they are often human-related.
Sources of pollution include dirt, bacteria, and fertilizers.