Ions are Atoms with more neutrons than protons
Atoms with a positive or negative charge
Atoms with no charge
Atoms with more protons than neutrons
Atoms that are joined together in fixed proportions

Ions are atoms with a positive or negative charge.

Explanation:

Ions are atoms or molecules that, when subjected to the phenomenon of ionization, gain or lose electrons, ceasing to be neutral and acquiring an electric charge.

The charge that atoms or molecules possess can be positive —if it has lost electrons— or negative when it acquires electrons. The negatively charged particle is called anion, and when it is positively charged cation.

The other options are not correct because of:

b. heterotroph

explanation:

all these collisions do one thing, and that thing is explained in the last option. when dusst, rocks and ice collide, they harden and form giant layers of rocks or hard ice.

d)   to harden materials to form different parts of earth’s layers

hope it ,

bioteacher101