Is it true when earth's ice increases, ocean water gets saltier

There are many chemicals in seawater that make it salty. Most of them get there from rivers carrying so yes

Yes, it is true; when water freezes into ice, salt is pushed downward and increases the salinity of the water trapped there. 

D. most models represent a real world object in a simpler way

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