Chemical Engineering Thermodynamics - Study Mode

[#356] If atmospheric temperature and dew point are nearly equal, then the relative humidity is
Correct Answer

(C) Almost 100%

Explanation

Solution: It is the point where the air becomes saturated and gives its first liquid bubble of more volatile substance in an solution this point corresponding temperature and pressure is called dew temperature and dew pressure.

[#357] First law of thermodynamics deals with the
Correct Answer

(D) None of these

Explanation

Solution: The First Law of Thermodynamics is a statement of the conservation of energy . It expresses that the total energy of an isolated system remains constant — energy can be transferred or transformed, but it cannot be created or destroyed. Option A: Direction of energy transfer This option is incorrect . While the first law deals with the amount of energy transferred , it does not determine the direction of energy flow. The Second Law of Thermodynamics addresses the direction of energy transfer — for example, heat naturally flows from a hotter body to a cooler one. Option B: Reversible processes only This option is incorrect . The First Law applies to all types of processes — both reversible and irreversible . It only accounts for the total energy balance and is not concerned with the nature of the process. Option C: Irreversible processes only This is also incorrect . As with Option B, the law is universal and does not distinguish between reversible and irreversible processes. It applies equally to both. Option D: None of these This is the correct answer . None of the listed options correctly describe what the First Law of Thermodynamics actually deals with. The first law is about energy conservation , not about direction (Option A), nor is it limited to any specific process type (Options B and C). Therefore, the correct answer is: None of these.

[#358] COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about
Correct Answer

(B) 3.5

Explanation

Solution: $$frac{{1kw}}{{ton}} = frac{{3.516}}{{c.o.p}}$$

[#359] The number of degree of freedom for an azeotropic mixture of ethanol and water in vapour-liquid equilibrium, is
Correct Answer

(B) 1

Explanation

Solution: For an azeotropic mixture since the composition of a constituent remains same in vapour and liquid one of the variable to define the system reduces. So, $$f = C - emptyset + 2$$ Given number of components $$= 2,$$ xa0number of phases $$= 2$$ So, degree of freedom $$= 1$$

[#360] Gibbs free energy of a pure fluid approaches __________ as the pressure tends to zero at constant temperature.
Correct Answer

(B) Minus infinity

Explanation

Solution: We know : $$G = {G^ circ } + RTlnfrac{f}{{{P^ circ }}}$$ $$ Rightarrow $$ where $${G^ circ }$$ and $${P^ circ }$$ are at standard states So, we can say when $${P^ circ } o 0, Rightarrow {G^ circ } o infty $$