Answer: Chromium is less reactive as compared to Aluminium as it can not easily electrons as aluminium.
Explanation:
The arrangement of metals in a series according to the decreasing order of their reactivity is called reactivity series.
The metals that are placed above hydrogen are more reactive and those below hydrogen are less reactive.
A metal placed above another metal can displace lower metal from its salt solution. Thus a metal placed above in series is more reactive than metals placed below it.
As aluminium can easily lose electrons as compared to chromium , it is more reactive than Chromium.