* Heat and Temperature: Heat is the total energy of the molecules in a substance, while temperature is a measure of the average kinetic energy of those molecules.

* Specific Heat Capacity: Lead has a specific heat capacity, meaning it takes a certain amount of energy to raise the temperature of 1 kg of lead by 1°C.

* Higher Temperature, More Energy: Since the lead at 400°C is at a higher temperature, its molecules are moving faster on average. This means they have more kinetic energy, and therefore, the entire 1 kg sample of lead has more total energy (heat).

In simpler terms: The hotter the object, the more energy its molecules have, and the more energy the object has overall.