Question

What happens to the particles in dry ice when it sublimes

Answer 1

Nothing more happens.

A compound changes state.Particles never change.Only change will be their intermolecular force.So in solid state dry ice has more intermolecular attraction forces between the molecules(or you may say particle) and after sublimation in gaseous state molecules have weak attraction forces between them.

Nothing happens to a particle.

Thanks.
Tripathy.

Answer 2

When the particles of ice sublime it get vaporised and after cooling it will turn in liquid state.