Which of the following is not the property of ionic compounds?
(i) Ionic compounds have low melting and boiling points.
(ii) Ionic compounds are generally soluble in water and insoluble in solvent such as kerosene, petrol etc.
(iii) Ionic compounds are solids and are somewhat hard because of the strong force of attraction between the positive and negative ions.
(iv) Ionic compounds conduct electricity in the molten state.

Correct option is C

The correct answer is (C) (i) Ionic compounds have low melting and boiling points.

Here's why:

• Strong Electrostatic Forces: Ionic compounds are formed by the strong electrostatic attraction between oppositely charged ions (cations and anions).
• High Melting and Boiling Points: To overcome these strong forces and break down the crystal lattice structure, a significant amount of energy is required. This translates to high melting and boiling points.

The other options are properties of ionic compounds:

• Solubility: Ionic compounds are generally soluble in polar solvents like water due to the interaction between the ions and the polar water molecules. They are insoluble in nonpolar solvents like kerosene and petrol.
• Hardness: The strong electrostatic forces between ions give ionic compounds a crystalline structure and make them relatively hard.  
• Electrical Conductivity: Ionic compounds conduct electricity in the molten state and when dissolved in water.

This is because the ions are free to move and carry electric charge.