6. A path 1-2-3 is given. A system absorbs 100 kJ as heat and does 60 kJ of work while along the path 1-4-3, it does 20 kJ of work. The heat absorbed during the cycle 1-4-3 is
9. When a system changes its state from one equilibrium state to another equilibrium state, then the path of successive states through which the system has passed, is known as