The three naturally occurring isotopes of potassium are 39K ; 40K ; and 41K .The percent natural abundances of 39K and 41K are 93.2581% and 6.7302% respectively. What is the natural abundance of 40K ?

The chemical bubbles

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

A.(nh4)(2co3)is the correct answer