Among the following statements, choose the correct statements,

A. In Ionic solid, ions are the constituent particles.

B. Ionic solids are soft.

C. Ionic solid are electrical insulators in the solid state.

D. Ionic solid conduct electricity in molten state.

E. Ionic solid have low melting and boiling points.

Choose the correct answer from the options given below:

Explanation: 

Statement A :

In Ionic solid, ions are the constituent particles. This is true because ionic solids are composed of positively charged metal ions and negatively charged non-metal ions, which are held together by electrostatic forces to form a crystal lattice.

Statement B :

Ionic solids are soft. This is an incorrect statements because ionic solids are generally hard and brittle.

Statement C :

Ionic solid are electrical insulators in the solid state. This is true because in the solid state, the ions in the crystal lattice are held in fixed positions and are not free to move, so they cannot conduct electricity.

Statement D:

Ionic solid conduct electricity in molten state. This is true because when ionic solids are heated to a high temperature, the crystal lattice breaks down and the ions become free to move, creating a liquid called a molten salt. In this state, the ions can carry an electric current and the substance can conduct electricity.

Statement E :

Ionic solid have low melting and boiling points. This is an incorrect statements because ionic solids typically have high melting and boiling points due to the strong electrostatic forces between the ions in the crystal lattice.

Conclusion : 

Therefore, the correct answer is option 1) A, C & D only.