Calculate the hydronium ion concentration in an aqueous solution with a poh of 9.85 at 25°c.

We have been given the pOH value, then we can calculate the pH value.
pH + pOH = 14
pOH = 9.85 
pH = 14 - 9.85 = 4.15
We can calculate the hydronium ion concentration using pH value
pH = -log [H₃O⁺]
[H₃O⁺] = antilog(-pH)
we can calculate antilog of pH by writing it as 10^(-4.15)
[H₃O⁺] = antilog (-4.15)
[H₃O⁺] = 7.07 x 10⁻⁵ M

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

What’s the solution?