In a vapour
compression refrigerator system, designed to maintain an enclosure at -3⁰C,
the equipment are so sized that all heat transfer units realize an approach of
5⁰C.
Cooling water is available at 32⁰C. What is the
maximum possible COP?
(A) 5.9
(B) 6.2
(C) 6.7
(D) 7.1
GATE
1987
Answer: (A)
Criterion of chemical equilibrium
is that the total Gibb’s free energy change is
(A) always positive
(B) always negative
(C) zero
(D) not specifically defined
GATE
1988
Answer: (C)
Entropy
is
(A) intensive property
(B) derived property
(C) extensive property
(D) None of the above
GATE
1989
Answer: (C)
For
gas and liquid phases in equilibrium a component in a non-ideal system follows
the relation
GATE
1989
Answer: (B)
The
system liquid water in equilibrium with a mixture of water vapour and nitrogen
has the following degrees of freedom
(A) 4
(B) 3
(C) 0
(D) 2
GATE
1990
Answer: (D)
At
318 K at total pressure of 24.4 KPa, the composition of the system ethanol (1)
ad toluene (2) at equilibrium is x1 = 0.3 and y1 = 0.64.
The saturation pressure at the given temperature for pure components are P1
= 23.06 KPa and P2 = 10.05 KPa respectively. What is the value of GE/RT
for the liquid phase?
(A) 0.41
(B) 0.51
(C) 0.58
(D) 0.62
GATE
1991
Answer: (A)
The binary mixture A – B forms an
azeotrope with a boiling point of 71.8⁰C at 1 bar
pressure, the azeotropic composition being 55 mole percent A. The pure
component vapour pressures at 71.8⁰C are A = 0.710
bar; B = 0.743 bar. Estimate the activity coefficient of A with liquid,
assuming the vapour to be an ideal.
(A) 1.40
(B) 1.56
(C) 1.61
(D) 1.68
GATE
1991
Answer: (A)
For
system in equilibrium at a given temperature and pressure
(A) The entropy must be minimum
(B) The enthalpy must be a minimum
(C) The internal energy must be minimum
(D) The Gibb’s free energy must be a minimum
GATE
1991
Answer: (D)
The
shape of T-S diagram for carnot cycle is
(A) A rectangle
(B) A rhombus
(C) A trapezoid
(D) A circle
GATE
1991
Answer: (A)
To obtained the integrated form of
Claussius-Clapeyron equation
from the exact Clapeyron equation,
it is assumed that
(A) The volume of the liquid phase is
negligible compared to that of the vapour phase
(B) The vapour phase behaves as an ideal gas
(C) The heat of vaporization is independent
of temperature
(D) All the above are applicable
GATE
1991
Answer: (D)
During
Joule-Thomson expansion of gases
(A) enthalpy remains constant
(B) entropy remains constant
(C) temperature remains constant
(D) none of these
GATE
1992
Answer: (A)
106
Jules of heat are transferred from a reservoir at 327⁰C
to an engine that operates an carnot cycle. The engine rejects heat to a
reservoir at 27⁰C. Determine the work
done by the engine?
(A) 0.5×106 Joules
(B) 0.6×106 Joules
(C) 0.7×106 Joules
(D) 0.8×106 Joules
GATE
1992
Answer: (A)
An inventor claims to have developed a refrigerator
unit which maintains the refrigerated space at - 3⁰C
while operating in a room when the room temperature is 27⁰C
and which has a coefficient of performance of 9.5. How do you evaluate his
claim?
(A) Inventors claim is feasible
(B) Inventor’s claim is not feasible
(C) Insufficient data to evaluate his claim
(D) None of these
GATE
1992
Answer: (B)
For
a single component, two phase mixture the number of independent variables are
(A) 2
(B) 1
(C) 0
(D) 3
GATE
1992
Answer: (A)
The
necessary and sufficient condition for equilibrium between two phases is
(A) Concentration of each component should be
same in the two components
(B) The temperature of each phase should be
same
(C) The pressure should be same in two phases
(D) The chemical potential of each component
should be same in two phases
GATE
1992
Answer: (D)
A rigid
insulated cylinder has two compartments separated by a thin membrane while one
compartment contains 1 kmol nitrogen at a certain temperature and pressure, the
other contains 1 kmol of CO2 at the same temperature and pressure.
The membrane is ruptured and the two gases are allowed to mix. Assume that the
gases behave as ideal gases. Calculate the increase in entropy of the contents
of the cylinder. Universal gas constant R = 8314 J/kmol.K.
(A) 11.53 KJ/K
(B) 12.52 KJ/K
(C) 13.25 KJ/K
(D) 14.51 KJ/K
GATE
1993
Answer: (A)
In the vicinity
of the triple point, the vapour pressure of liquid and solid ammonia, are
respectively given by
Where P in atm
and T in K. What is the temperature at the triple point?
(A) 195 K
(B) 203 K
(C) 250 K
(D) 275 K
GATE
1993
Answer: (A)
The
relationship (∂T/∂P)H= 0 holds good for
(A) an ideal gas at any state
(B) a real gas at any state
(C) any gas at its critical state
(D) any gas at its inversion point
GATE
1993
Answer: (A)
During
the change of phase of pure substance
(A) dG = 0
(B) dP = 0
(C) dH = 0
(D) dV = 0
GATE
1993
Answer: (A)
At
the triple point of a pure substance, the number of degrees of freedom is
(A) 0
(B) 1
(C) 2
(D) 3
GATE
1993
Answer: (A)
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