If 3 kg of a substance with a specific latent heat of vaporisation of 2,260,000 J/kg is vaporised, how much energy is required (Changes of state and specific latent heat) (Changes of state and specific latent heat; definition focus: Calculate mass when energy transferred and specific latent heat are known) (Changes of state and specific latent heat; definition focus: Calculate mass when energy transferred and specific latent heat are known)

The correct answer is 6,780,000 J.

Boundary lens: Keep this separate from nearby specification points that use similar words but test a different idea. This question asks: If 3 kg of a substance with a specific latent heat of vaporisation of 2,260,000 J/kg is vaporised, how much energy is required (Changes of state and specific latent heat) (Changes of state and specific latent heat; definition focus: Calculate mass when energy transferred and specific latent heat are known) (Changes of state and specific latent heat; definition focus: Calculate mass when energy transferred and specific latent heat are known). The correct response is 6,780,000 J, because density links mass and volume, so the answer must preserve which quantity is being calculated. In Changes of state and specific latent heat, the marking point should connect directly to calculate mass when energy transferred and specific latent heat are known. 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 Internal energy and energy transfers, 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 406 is distinct because it uses this exact question context and the boundary lens rather than a generic particle-model sentence.