Which law of thermodynamics implies that no heat engine can be `100%` efficient?

Which of the following laws of thermodynamics forms the basis for the definition of temperature?

Which law of thermodynamics help in calculating entropy at different temperatures?

Which one of the following equations correctly represent the first law of thermodynamics for the given process occuring in an ideal gas

Thermodynamics deals with energy changes of macroscopic system. a) Consider a chemical reaction taking place in a closed insulated vessel. To which type of thermodynamic system does it belong? b) State the first law of thermodynamics. c) 3 mol of an ideal gas at 1.5 atm and 25^oC expands isothermally in a reversible manner to twice its original volume against an external pressure of 1 atm. Calculate the work done. [R = 8.314 JK^-1mol^-1]