Calculate the amount of heat required to melt 2 kg of lead taken at the melting point.

To calculate the cost of heat for melting 2 kg of lead, we apply the formula: Q = λ * m.

Constants and variables: λ – specific heat of fusion of lead (λ = 0.25 * 10 ^ 5 J / kg); m is the mass of lead (m = 2 kg).

Let’s perform the calculation: Q = λ * m = 0.25 * 10 ^ 5 * 2 = 50 * 10 ^ 3 J (50 kJ).

Answer: To melt 2 kg of lead, you need to spend 50 kJ of heat.