Q1(10pts).A 40W heat source is applied to a gas sample for 25s, during which time the gas expands and does 750 J of work on its surroundings. By how much does the internal energy (in J ) of the gas change? Please show your calculations. Q2(10pts). Calculate S (in J/K) for the reaction C2H2(g)+H2(g)C2H4(g), if standart the entropies (in JK1mol1 ) of C2H2(g),H2(g) and C2H4(g) are 200.8,130.58 and 219.4 , respectively? Please show your calculations. Q3(10pts). Heat is transferred directly from a heat reservoir at 270C to another heat reservoir at 5C. If the amount of heat transferred is 100kJ, what is the total entropy change (in JJ/K ) as a result of this process? Please show your calculations. Q4(25pts).Determine the heat input (in kJ ) to a Carnot engine that operates between 350C and 25C, and produces 100kJ of work? Please, show your calculations. Q5(20pts).A cyclic machine (see figure right) receives 325kJ from a 1000K energy reservoir. It rejects 125kJ to a 400K energy reservoir, and the cycle produces 200kJ of work as output. Is this cycle reversible, irreversible or impossible? Please show your calculations. Q6(25pts). Two Carnot refrigerators operate in series between two reservoirs maintained at 30C and 150C, respectively. The energy output by the first refrigerator is used as the heat energy input to the second refrigerator. If the coefficient of performances of the two refrigerators are the same, determine the intermediate temperature (in C ) by showing your calculations