Pick out the correct statement.
Compression ratio of an Otto engine is comparatively higher than a diesel engine
Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio
Otto engine efficiency decreases with the rise in compression ratio, due to decrease in work produced per quantity of heat
Diesel engine normally operates at lower compression ratio than an Otto engine for an equal output of work
Correct Answer :
B. Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio
Related Questions
__________ functions are exemplified by heat and work.
Path
Point
State
None of these
What is the degree of freedom for a system comprising liquid water equilibrium with its vapour?
0
1
2
3
The efficiency of a Carnot heat engine operating between absolute temperatures T1 and T2 (when, T1 > T2) is given by (T1 - T2)/T1. The co-efficient of performance (C.O.P.) of a Carnot heat pump operating between T1 and T2 is given by
T1/(T1-T2)
T2/(T1-T2)
T1/T2
T2/R1
With increase in pressure (above atmospheric pressure), the Cp of a gas
Increases
Decreases
Remains unchanged
First decreases and then increases
During the phase transition, __________ changes.
Pressure
Volume
Temperature
All (A), (B) and (C)
Compressibility factor of a gas is
Not a function of its pressure
Not a function of its nature
Not a function of its temperature
Unity, if it follows PV = nRT
Pick out the wrong statement.
A refrigeration cycle violates the second law of thermodynamics
Refrigeration cycle is normally represented by a temperature vs. entropy plot
In a refrigerator, work required decreases as the temperature of the refrigerator and the temperature at which heat is rejected increases
One ton of refrigeration is equivalent to the rate of heat absorption equal to 3.53 kW
In the decomposition of PCl5 represented by, PCl5 PCl3 + Cl2, decrease in the pressure of the system will __________ the degree of dissociation of PCl5.
Increase
Decrease
Not alter
None of these
In Joule-Thomson porous plug experiment, the
Enthalpy does not remain constant
Entire apparatus is exposed to surroundings
Temperature remains constant
None of these
Entropy of the system decreases, when
Snow melts into water
A gas expands spontaneously from high pressure to low pressure
Water is converted into ice
Both (B) & (C)
Which of the following has the minimum value of COP for a given refrigeration effect?
Reverse Carnot cycle
Ordinary vapour-compression cycle
Vapour-compression process with a reversible expansion engine
Air refrigeration cycle
Cv for an ideal gas
Does not depend upon temperature
Is independent of pressure only
Is independent of volume only
Is independent of both pressure and volume
Near their critical temperatures, all gases occupy volumes __________ that of the ideal gas.
Less than
Same as
More than
Half
The ammonia synthesis reaction represented by N2 + 3H2 2NH3; ΔH = - 22.4 kcal, is
Endothermic
Exothermic
Isothermal
Adiabatic
The change in Gibbs free energy for vaporisation of a pure substance is
Positive
Negative
Zero
May be positive or negative
Air-refrigeration cycle
Is the most efficient of all refrigeration cycles
Has very low efficiency
Requires relatively large quantities of air to achieve a significant amount of refrigeration
Both (B) and (C)
Gibbs-Helmholtz equation is
ΔF = ΔH + T [∂(ΔF)/∂T]P
ΔF = ΔH - TΔT
d(E - TS) T, V < 0
dP/dT = ΔHvap/T.ΔVvap
Rotary lime kiln is an example of a/an __________ system.
Closed
Open
Isolated
Non-thermodynamic
Variation of equilibrium pressure with temperature for any two phases of a given substances is given by the __________ equation.
Gibbs-Duhem
Maxwell's
Clapeyron
None of these
In the equation, PVn = Constant, if the value of n = 0, then it represents a reversible __________ process.
Isobaric
Isothermal
Isentropic
Isometric
The equation, PV = nRT, is best obeyed by gases at
Low pressure & high temperature
High pressure & low temperature
Low pressure & low temperature
None of these
Minimum number of phases that exists in a system is 1. Number of chemical species in a colloidal system is
1
2
3
4
For an exothermic reaction
Only enthalpy change (ΔH) is negative
Only internal energy change (ΔE) is negative
Both ΔH and ΔE are negative
Enthalpy change is zero
Generation of heat by friction is an example of a/an __________ change.
Isothermal
Irreversible
Adiabatic
Reversible
Pick out the correct statement.
Compression ratio of an Otto engine is comparatively higher than a diesel engine
Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio
Otto engine efficiency decreases with the rise in compression ratio, due to decrease in work produced per quantity of heat
Diesel engine normally operates at lower compression ratio than an Otto engine for an equal output of work
Pick out the wrong statement.
Trouton's ratio of non-polar liquids is calculated using Kistyakowsky equation
Thermal efficiency of a Carnot engine is always less than 1
An equation relating pressure, volume and temperature of a gas is called ideal gas equation
None of these
The temperature at the eutectic point of the system is the __________ temperature that can be attained in the system.
Lowest
Highest
Average
None of these
Entropy is a measure of the __________ of a system.
Disorder
Orderly behaviour
Temperature changes only
None of these
Pick out the wrong statement.
Cp of monatomic gases such as metallic vapor is about 5 kcal/kg.atom
The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state
There is an increase in entropy, when a spontaneous change occurs in an isolated system
At absolute zero temperature, the heat capacity for many pure crystalline substances is zero
The value of gas constant 'R' is
1.987 cal/gm mole °K
1.987 BTU/lb. mole °R
Both (A) and (B)
Neither (A) nor (B)