If an automobile engine burns petrol at a temperature of 816° C and if the surrounding temperature is 21° C, calculate its maximum possible efficiency

Calculate the entropy change in the engine that receives 957.5 kJ of heat reversibly at 110°C temperature.

Calculate the standard entropy change for the following reaction (Δs_f⁰), given the standard entropies of CO_2(g) ,  C_(s) 'O_2(g) as 213.6, 5.740, and 205 JK^-1 respectively.

Calculate the entropy change during the melting of one mole of ice into water at 0°C and 1 atm pressure. Enthalpy of fusion of ice is 6008 J mol^-1.

The entropy change in the conversion of water to ice at 272 k for the system is -22.88 Jk^-1mol^-1 and that of surrounding is + 24.85 Jk^-1 mol-¹, State whether the process is spontaneous or not?