Question 1:
easy
The efficiency of heat engine working between \(27^\circ\text{C}\) and \(327^\circ\text{C}\) may be
The maximum possible efficiency (Carnot efficiency) is \(eta_{\text{max}} = 1 - \frac{T_L}{T_H} = 1 - \frac{300}{600} = 50\%\). Practical heat engines have efficiency less than or equal to 50%, so 50%, 35%, and 25% are all possible values.