The diagrams below show particle arrangements in four substances at room temperature.
Diagram A: particles closely packed in a regular, fixed pattern.
Diagram B: particles closely packed but able to slide past each other.
Diagram C: particles far apart, moving rapidly in all directions.
Diagram D: particles closely packed in a regular, fixed pattern, more tightly packed than in Diagram A.
aIdentify which diagram represents a gas. [1]
bDiagram D represents a substance that is denser than the solid in Diagram A. Deduce the state of matter of the substance in Diagram D, and explain one limitation of using particle diagrams alone to distinguish between the two solids. [2]
cBromine is a liquid at room temperature (melting point −7 °C, boiling point 59 °C) but becomes a gas when heated above 59 °C. Explain, using particle behaviour, why bromine transitions from the arrangement in Diagram B to the arrangement in Diagram C as it is heated. [1]