Solution:Concept- We are aware that the list of metals in the activity series is arranged in declining order of their reactivities. The reactivity series tells us if one metal may completely replace another in a displacement process. It also offers information on how reactive metals are to acids and water. For instance, Mg metal is more reactive than element hydrogen because it can remove hydrogen ions from its solution.
As the series progresses, it becomes harder for a metal in solution to lose an electron or electrons and create a positive ion. specifically, from potassium to gold.
The activity series includes hydrogen because, like metals, it too loses an electron and becomes positively charged (H +) throughout the majority of chemical processes.
The series makes it easier to compare metals in terms of how reactive they are.
It is also simple to compare the compounds of the metals (oxygen, carbonates, nitrates, and hydroxides).
Hence, the correct option is 4.