First Law

For the isothermal expansion of an ideal gas in a piston cylinder system, the net heat supplied during the process is equal to the net work. Which one of the following statements i...

A thermodynamically closed system contains 1 kg of hydrogen. The system undergoes a reversible polytropic process with polytropic index 1.3. The work output during the process is 4...

Which of the following relationships is valid only for reversible process undergone by a closed system of simple compressible substance (neglect changes in kinetic and potential en...

A $$100$$ $$W$$ electric bulb was switched on in a $$2.5 \times 3 \times 3m$$ size thermally insulated room having temperature of $${20^0}C.$$ Room temp at the end of $$24$$ hours...

A gas contained in a cylinder is compressed, the work required for compression being $$5000$$ $$kJ.$$ During the process, heat interaction of $$200$$ $$kJ$$ causes the surroundings...

Considering the relationship $$TdS=dU+PdV$$ between the entropy $$(S),$$ internal energy $$(U),$$ pressure $$(P),$$temperature $$(T)$$ and volume $$(V),$$ Which of the following st...

A steam turbine receives steam steadily at $$10$$ $$bar$$ with an enthalpy of $$3000$$ $$kJ/kg$$ and discharges at $$1$$ bar with an enthalpy of $$2700$$ $$kJ/kg.$$ The work output...

A certain mass of a pure substance undergoes an irreversible process from state $$1$$ to state $$2,$$ the path of the process being a straight line on the $$T$$-$$s$$ diagram. Calc...

An insulated rigid vessel contains a mixture of fuel and air. The mixture is ignited by a minute spark. The contents of the vessel experience.

The first law of thermodynamics takes the form $$W = - \Delta \,H$$ when applied to :