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The property of a working substance which increases or decreases as the heat is supplied or removed in a reversible manner is known as.
Select one:
Hence, entropy increases or decreases as heat is supplied or removed in reversible manner.
The correct answer is: entropy
An ideal gas has temperature T_{1} at the initial state i shown in the pV diagram here. The gas has a higher temperature T_{2} at final states a and b, which it can reach along the path shown. The entropy change along the path to state a is
Select one:
From i to a and i to b, change in temperature is same, hence dU remains same for both the processes. But i to a is isochoric process, hence work done is zero.
⇒ heat gained in process a is smaller, hence the entropy change along the pathto state a is smaller than b.
The correct answer is: smaller than b
The TS diagram of two cycles for the operation of an engine are shown in figure below.
The numerical values of the parameters T_{1} , T_{2} , S_{1} and S_{2} in the two figures are the same. Which cycle has greater efficiency?
Select one:
Efficiency
Available energy per cycle is = Q_{1} – Q_{2}
= Area of curve ABC
Q_{1} = Total area of curve (ABCD)
⇒ Area of curve is same for both figures, but total area is more for figure 1.
⇒
Hence, second figure, has greater efficiency
The correct answer is: Second
The difference in entropy between a state of volume V_{i} and a state of volume of V_{f} (temperature and number of molecules remaining constant) is equal to.
Select one:
dS =
for constant temperature, dU = 0
and
The correct answer is:
The efficiency of the Carnot cycle may be increased by.
Select one:
if T_{L} is reduced, η can be increased.
The correct answer is: decreasing the lowest temperature
KelvinPlank’s law deals with
Select one:
KelvinPlank statement of the second law of thermodynamics states that it is impossible to devise a cyclically operating device, the sole effect of which is to absorb energy in the form of heat from a single thermal reservoir and to deliver an equivalent amount of work.
The correct answer is: conversion of heat into work
In a reversible process, entropy of the system.
Select one:
For all reversible processes and constitutes part of the second law of thermodynamics, the entropy of the universe remains constant in a reversible process.
1gm of perfect gas at volume V_{A} , pressure p_{A} and temperature T_{A} changes from state A to state B when volume is V_{B}, pressure is p_{B} and temperature T_{B}. the change in entropy is.
Select one:
Change in entropy
pV = RT
The correct answer is:
Change in entropy depends
Select one:
Entropy is a measure of the number of microscopic configurations that a thermodynamic system can have when in a state as specified by some macroscopic variable.
The correct answer is: on the thermodynamic state
In an irreversible process, the entropy of the universe.
Select one:
When dealing with a system that is not isolated from its surroundings, remember that the increase in entropy described in the second law is that of the system and its surroundings. When a system and its surrounding interact in an irreversible process, the increase in entropy of one is greater than the decrease in entropy of the other. Hence, we conclude that the change in entropy of the universe must be greater than zero for an irreversible process and equal to zero for a reversible process.
The correct answer is: increases
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