If 4 kg of a substance is heated and absorbs 1,200 J of energy, resulting in a temperature change of 15°C, what is the specific heat capacity of the substance (Temperature changes in a system and specific heat capacity) (Temperature changes in a system and specific heat capacity; equation and unit focus: Rearrange the specific heat capacity equation for any required variable) (Temperature changes in a system and specific heat capacity; particle reasoning focus: Rearrange the specific heat capacity equation for any required variable)

The correct answer is 20 J/kg°C.

Unit lens: Check the units before giving the final statement so the physics quantity is not swapped. This question asks: If 4 kg of a substance is heated and absorbs 1,200 J of energy, resulting in a temperature change of 15°C, what is the specific heat capacity of the substance (Temperature changes in a system and specific heat capacity) (Temperature changes in a system and specific heat capacity; equation and unit focus: Rearrange the specific heat capacity equation for any required variable) (Temperature changes in a system and specific heat capacity; particle reasoning focus: Rearrange the specific heat capacity equation for any required variable). The correct response is 20 J/kg°C, because specific heat capacity links energy, mass, material and temperature change. In Temperature changes in a system and specific heat capacity, the marking point should connect directly to rearrange the specific heat capacity equation for any required variable. 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 325 is distinct because it uses this exact question context and the unit lens rather than a generic particle-model sentence.