Answer: Ions are fixed in their lattice positions in the solid state but become free to move on melting.
- A The electrons are said to become delocalised mainly once the solid is melted in routine practice
- B Ions are fixed in their lattice positions in the solid state but become free to move on melting
- C Rising temperature is said to change the overall electron density of the ions overall in most cases
- D The bonds are said to become ionic in character mainly after melting occurs under typical conditions
Correct answer: B. Ions are fixed in their lattice positions in the solid state but become free to move on melting
Explanation: In solid ionic compounds, ions are held rigidly in the crystal lattice. When melted, they become free to move and carry current.
The three cubic unit cells: Simple Cubic has atoms only at corners; Body-Centred adds one atom at the centre; Face-Centred adds one atom at the centre of each of the 6 faces, giving the highest packing efficiency.
Concept context
Explore the ordered world of crystalline solids: unit cells, packing, defects, and how structure determines electrical and magnetic properties.