Why is Helium and inert gas​

This is because a helium atom is loath to give up its two electrons, which perfectly fill its only electron shell. ... Elements with shells that are already full and have no electrons to lend are called noble gases—and helium, the smallest of these, is considered the most inert.20 Mar 2018

The activity series is shown in the attached picture. if the element is below the other, then you can displace the other. following the activity series as a guide, the reactions are as follows: nickel and aluminum chloride3 ni + 2 alcl₃  → 3 nicl₂ + 2 albarium and copper bromideba + cubr  →  no reaction because cu is less oxidizable than bapotassium nitrate and aluminum3 kno₃ + al  → al(no₃)₃ + 3 ksodium phosphate and zincnaso₄ + zn  → znso₄ + na