Which particles conduct electricity in: a) Molten lead (II) bromide b) Lead metal 6. Explain why melting points of NaCl and MgCl2 are higher than those of SiCl4, PCl3 and SCl2 chlorides?

Here are the answers to your questions:

5. Which particles conduct electricity in:

a) Molten lead (II) bromide
✅ Correct. The particles are ions ($\text{Pb}^{2+}$ and $\text{Br}^{-}$).

b) Lead metal
✅ Correct. The particles are delocalized electrons.

6. The information in the table below relates to the physical properties of the chlorides of certain elements.

a) Explain why melting points of $\text{NaCl}$ and $\text{MgCl}_2$ are higher than those of $\text{SiCl}_4$, $\text{PCl}_3$ and $\text{SCl}_2$ chlorides in the table above.
$\text{NaCl}$ and $\text{MgCl}_2$ are ionic compounds with strong electrostatic forces of attraction between oppositely charged ions in a giant ionic lattice structure. A large amount of energy is required to overcome these strong forces, resulting in high melting points.
$\text{SiCl}_4$, $\text{PCl}_3$, and $\text{SCl}_2$ are covalent compounds that exist as simple discrete molecules. The forces between these molecules are weak intermolecular forces (van der Waals forces). Only a small amount of energy is required to overcome these weak forces, leading to low melting points.