81) The heating and expanding of a gas is called thermodynamic system.

82) Otto cycle efficiency is higher than Diesel cycle efficiency for the same compression ratio and heat input because in Otto cycle

83) Liquid fuels have higher calorific value than solid fuels.

84) The free expansion process is __________ non-flow process.

85) A mixture of gas expands from 0.03 m³ to 0.06 m³ at a constant pressure of 1 MPa and absorbs 84 kJ of heat during the process. The change in internal energy of the mixture is