Which of these energy transformations is not part of how a nuclear power plant provides electrical energy to a home?
changing electrical energy to chemical energy
changing thermal energy to mechanical energy
changing nuclear energy to thermal energy
changing mechanical energy to electrical energy

I think the second one

If the heat engine is a perfect carnot cycle engine, thenefficiency = (t2-t1)/t2   where t1=temperature of cold reservoir ( ° k) = 135            t2=temperature of hot reservoir ( ° k)   = 325thereforeefficiency = (t2-t1)/t2 = (325-135)/325 = 0.5846 = 58%  note: this is the theoretical maximum efficiency of a perfect heat engine.   real-life engines do not achieve this value.