Most solids a. are dense and difficult to compress b. are able to flow c. are amorphous d. have a disorderly structure

Most solids a) are dense and difficult to compress.

Most solids are closely compacted, their molecules are close together and vibrate. They don't move freely like gas or water molecules do.
They are difficult to be squeezed or flattened.

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