To heat the lead part by 10 degrees, 1.4 kJ of heat was spent. What is the mass of the part?

You need to convert kJ to J (SI system)
1 kJ = 1000 J, therefore 1.4 kJ = 1400 J
The formula for the amount of heat Q = cmΔt, where c is the specific heat capacity of the substance (tabular value), m is the mass, Δt is the temperature change during the process
We express m, m = Q / (c × Δt)
Substitute the numbers, m = 1400 / (140 × 10) = 1 kg.
Answer 1 kg