Under which of the following conditions can potassium bromide (KBr) conduct electricity?

• A. When in solid crystalline form
• B. When mixed with sand
• C. When cooled to very low temperatures
• D. When dissolved in water

Answer: (D)

Verified step by step guidance

1. Understand that electrical conductivity in ionic compounds like potassium bromide (KBr) depends on the presence of free-moving charged particles (ions).
2. Recognize that in solid crystalline form, KBr ions are fixed in a rigid lattice and cannot move freely, so it does not conduct electricity.
3. Consider that mixing KBr with sand does not provide a medium for ion movement, so conductivity will not occur.
4. Note that cooling KBr to very low temperatures generally reduces ion mobility further, decreasing conductivity.
5. Identify that when KBr is dissolved in water, it dissociates into K⁺ and Br⁻ ions, which are free to move and carry electric current, allowing the solution to conduct electricity.