Solution:
Concept- The reactivity series is a chart in which metals are arranged in order of their reactivity.The features of the reactivity series are-
● Metals at the top of the reactivity series are strong reducing agents because they oxidise easily. These metals tarnish/corrode very easily.
● The reducing power of metals weakens as you go through the series.
● Electropositivity of elements also decreases as one moves down the metal reactivity series.
● All metals above hydrogen in the activity range release hydrogen gas when reacted with dilute or dilute .
● Metals that are higher in the reactivity series have the ability to displace metals that are lower from their salt solutions.
Thus, the metals which are found at the top of the series are most reactive and metals that are placed at the bottom of the reactivity series are the least reactive.
Therefore, the reactivity series of metals is basically the decreasing order of reactivity of the metals.
Hence, the correct answer is 3.
