What is the main difference between boiling and evaporation?

The correct answer is Boiling occurs throughout the liquid, evaporation occurs at the surface.

Exam lens: Write the relationship, substitute values only when needed, and finish by interpreting the result. This question asks: What is the main difference between boiling and evaporation. The correct response is Boiling occurs throughout the liquid, evaporation occurs at the surface, because changes of state are explained by particle energy and arrangement. In Changes of state, the marking point should connect directly to explain freezing using decreased particle energy and changed particle arrangement. If the question includes values, the working must keep the appropriate unit and operation; if it is an explanation, it must name the relevant particle behaviour or energy change. This item belongs to Changes of state and the particle model, so avoid answers that switch to a different quantity, confuse heat with temperature, or describe gas pressure without collisions when collisions are the reason. Checkpoint 131 is distinct because it uses this exact question context and the exam lens rather than a generic particle-model sentence.