4. For an air standard Otto engine cycle shown below, calculate the compression ratio and thermal efficiency of the engine. Assume air is ideal gas with a constant CP of 29.2 J/(molK) and enters the engine at 25C and 1atm. If PD=5atm, determine: 1 ) compression ratio of the engine; 2) thermal efficiency of the engine; and 3) assume 10 kJ/mol of combustion heat is generated by each explosion, the temperatures pressures and molar volumes at Points A, B, C, and D