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According to the Kelvin-Planck statement of the Second Law of Thermodynamics, which process is impossible?
The NCERT (Physics) text directly states the Kelvin-Planck statement: 'No process is possible whose sole result is the absorption of heat from a reservoir and complete conversion of the heat into work.'
A process is considered quasi-static if:
The NCERT (Physics) text defines a reversible process as 'quasi-static (system in equilibrium with the surroundings at every stage)'. A process being quasi-static is a key characteristic of reversibility, implying constant near-equilibrium.
Which of the following processes would likely be irreversible?
The NCERT (Physics) text lists 'Cooking gas leaking from a gas cylinder in the kitchen diffuses to the entire room. The diffusion process will not spontaneously reverse and bring the gas back to the cylinder' as an example of an irreversible process. Options o1, o3, and o4 describe conditions that approach reversibility.
What is the consequence of irreversibility in a practical heat engine according to thermodynamics?
The NCERT (Physics) text states: 'All other engines involving irreversibility in any way (as would be the case for practical engines) have lower than this limiting efficiency [of an ideal reversible engine].' Irreversibility is associated with dissipative effects which lower efficiency.
When considering changes in infinite steps during compression, what does the shaded area in a pV-plot (like Fig. 5.5 (c) mentioned in Chemistry NCERT) represent?
The NCERT (Chemistry) text, accompanying Fig. 5.5 (c), states: 'Work done on the gas is represented by the shaded area.' This refers to the integral of $p dV$, which represents work done.
A Carnot engine, an ideal reversible engine, operates between two temperatures. Which types of processes constitute its cycle?
The NCERT (Physics) text states: 'The Carnot cycle consists of two isothermal processes connected by two adiabatic processes.'
The concept of reversibility is crucial in thermodynamics because:
The NCERT (Physics) text highlights the importance of reversibility: 'But what is the highest efficiency possible for a heat engine working between two reservoirs at temperatures T1 and T2? It turns out that a heat engine based on idealised reversible processes achieves the highest efficiency possible.' This means it sets the theoretical maximum efficiency.
An idealised reversible process requires the absence of:
The NCERT (Physics) text states: 'The idealised reversible process is a quasi-static process with no dissipative factors such as friction, viscosity, etc.'
Which of the following describes the interaction between a parasite and its host?
According to the NCERT text, 'In both parasitism and predation only one species benefits (parasite and predator, respectively) and the interaction is detrimental to the other species (host and prey, respectively).' Therefore, one organism benefits, and the other is affected (harmed).
Which of the following is NOT an adaptation observed in endoparasites compared to ectoparasites?
The NCERT text states: 'The life cycles of endoparasites are more complex because of their extreme specialisation. Their morphological and anatomical features are greatly simplified while emphasising their reproductive potential.' Therefore, less complex life cycles is incorrect.
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