During a freezing winter night, water vapor (H2O\text{H}_2\text{O}H2O gas) in the air transforms directly into frost (H2O\text{H}_2\text{O}H2O solid) on a cold metal gate. Which statement correctly describes this transition under the particle model of matter?
The process is called sublimation; it is a chemical change because covalent bonds are broken, and the average kinetic energy of the molecules decreases.
The process is called deposition; it is a physical change because the molecular identity is unchanged, and the potential energy of the molecules decreases.
The process is called condensation; it is a physical change because it is reversible, and the potential energy of the molecules increases.
The process is called deposition; it is a chemical change because energy is released to the surroundings, and the average kinetic energy of the molecules increases.
27 exam-style questions on OCR GCSE Chemistry The particle model. Each one has a worked solution and a mark scheme showing where the marks go.