Answer: the ionized particles have no fix shape and volume
Explanation: Solid is the state of matter in which particles have strongest forces of attraction and thus have no vacant spaces and cannot be compressed. The volume and shape of the solids is fixed.
Liquid is the state of matter in which particles have weak forces of attraction and have vacant spaces between the particles. The volume of liquids is fixed and they acquire the shape of the container.
Gas is the state of matter in which particles have weakest forces of attraction and have large vacant spaces between the particles and thus can be compressed on applying force. The volume and shape of gases is not fixed.
Plasma is the state of matter which consists of ionized gas at high temperature. Thus have large vacant spaces between the particles as in gas and thus can be easily compressed. The volume and shape of plasma is not fixed.