Among the following statements, choose the correct statements.

A. In ionic solids, ions are the constituent particles.

B. Ionic solids are soft.

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

D. Ionic solids conduct electricity in molten state.

E. Ionic solids have low melting and boiling point.

Choose the correct answer from the options given below:

A, C, and D only

A. Ionic compound form because of the transfer of an electron from one atom to another, this transfer of an electron from one atom to another create ions and they will become the main constituents of an ionic compound. When combined, two or more two atoms will form a molecule and ions are the charged atom. Charged atom means they accepted or donated electrons.

C. In ionic compounds, electricity is conducted by ions. In a solid state, ions are held together by strong electrostatic forces and are not free to move about within the solid. Hence, in a molten state or in solution form, the ions are free to move and can conduct electricity. Hence, they are electrical insulators in solid state.

D. The conduction of electricity through a solution involved the movement of charged particles. A solution of an ionic compound in water contains ions that can move to the oppositely charged electrodes when electricity is passed through a solution. Ionic compounds in solid-state do not conduct electricity because the movement of ions in solid is not possible due to their rigid structure.  Ionic compounds conduct electricity in the molten state because in the molten state, the electrostatic force of attraction between the oppositely charged ions is overcome due to the heat which is provided to the ionic solid to change it from a solid state to a liquid state. The heat provided weakens the electrostatic force of attraction between the ions and thus the ions move freely and conduct electricity. For example, when NaCl in the solid state is heated then it decomposes to form a cation and anion as follows:

\(NaCl(s) \overset{Heat}{→}Na^+(l) + Cl^−(l)\)

This reaction is called the thermal decomposition reaction and after the solid NaCl is converted into molten NaCl, it can easily conduct electricity due to the free movement of Na⁺ and C^l− ions.