The correct choice is:
“It does not conduct electricity because its ions cannot move freely within the solid.”

Quick Scoop: What’s Going On?

In the particulate model for an ionic solid, you see alternating positive and negative ions locked into a rigid, repeating lattice. Because these ions are fixed in place, they cannot move through the solid, so no electric current can flow in the solid state.

When an ionic compound is melted or dissolved in water, the ions are free to move, and then it can conduct electricity. But in the solid lattice pictured in this type of question, the key idea is: ions present but not mobile → no conductivity.

Why the Other Options Are Wrong

  • “It conducts electricity because it is made of positive and negative ions.”
    Just having ions is not enough; they must be able to move. In a solid lattice, they are locked in place.
  • “It conducts electricity because it is made of particles of different sizes.”
    Particle size has nothing to do with electrical conductivity here.
  • “It does not conduct electricity because there are small spaces between the particles.”
    The presence of “small spaces” is not the controlling factor; ion mobility is.

So, for questions worded like:

“Which of the following correctly indicates whether the solid represented by the particulate model shown above conducts electricity and explains why or why not?”

you should select the option that says the solid does not conduct because its ions cannot move freely within the solid.

TL;DR: A solid ionic lattice does not conduct electricity since its ions are not free to move; pick the answer that says exactly that.