UNIT#05 THERMODYNAMICS Flashcards
The heat was given to a body, which raises its temperature by 1°C is _____.
Specific Heat
The thermal capacity of 40g of aluminium (specific heat 0.2 cal0g-1C-1) is _____.
8 cal0C-1
Thermal capacity=mc
80g of water at 30°C is poured on a large block of ice which is at 0°C. The mass of ice
30 g
Mud houses are cooler in summer and warmer in winter because;
Mud is a bad conductor of heat
The heat capacity of a substance is infinite. It means ____
No change in temprature
The change in internal energy, when a gas is cooled from 927°C to 27°C is?
75%
U=mcΔT
Two cylinders of equal size are filled with an equal amount of ideal diatomic gas at room temperature. Both the cylinders are fitted with pistons. In-cylinder A the piston is free to move, while in cylinder B the piston is fixed. When the same amount of heat is added to cylinder A raises by 20K. What will be the rise in the temperature of the gas in cylinder B?
28K
The relation for the 1st law of thermodynamics can be expressed as:
ΔQ = ΔU + ΔW
Examples of the first law of thermodynamics are;
➡Working on a bicycle pump
➡Brakes applied by an automobile
➡Human Metabolism
1st law of thermodynamics is a consequence of the conservation of:
Energy
Which statement about the first law of thermodynamics is correct?
The increase in the internal energy of a system equals the heating of the system minus the work done by the system
In a thermodynamic system working substance is an ideal gas, its internal energy is in the form of;
Kinetic Energy only
➡Adiabatic Process
(Ideal gas possesses only K.E)
In an ideal gas, the molecules possess?
Ony K.E
Which one is true for internal energy?
➡It is the sum of all forms of molecular energies of the system
➡It is proportional to translational K.E of the molecules
➡It is a state function of a system
If two systems X and Y are in thermal equilibrium. If X is heated at constant volume and Y is heated at constant pressure, and again finally maintained at thermal equilibrium, then heat given to the systems X and Y and internal energy U stored in the systems X and Y are;
➡Qx < Qy
➡Ux = Uy
The internal energy of a body is maximum when its temperature is;
273K
(Internal Energy ∝ Translational K.E ∝ Temperature
An ideal gas is pressed at a constant temperature,. Its internal energy
Remains the same
When 20J of work was done on the gas, 40J of heat energy was released. If the initial internal energy of the gas was 70J, what is the final internal energy?
50J
Q = ΔU - W
By rubbing the objects together, their internal energy;
Increases
The internal energy of an ideal gas depends upon only;
Temperature
If a system undergoes contraction of volume, then the work done by the system will be:
Negative
The work done in the isochoric process is;
Zero
(W=PΔV)
➡As volume is constant, so ΔV=0
Work done by air when it expands from 50 litres to 150 litres at a constant pressure of 2 atm is;
2 x 10^4 J
The equation W = P(V2 -1 V1) represents work done by the gas in;
an expansion at constant pressure
Find the change in internal energy of the system when a system absorbs 2 kilocalories o heat and at the same time does 500 joules of work;
7900 J (Q = W + ΔU)
A system is described in terms of thermodynamics variable;
➡Pressure
➡Temperature
➡Volume
The concept of temperature is related to;
Zeroth Law of thermodynamics
Which of the following statement is correct or any thermodynamic system?
➡The internal energy changes in all processes❌
➡The change in entropy can never be zero❌
➡Internal energy and entropy are state functions ✅
➡The work done in an adiabatic process is always zero❌
Thermodynamics is the study of the relationship between;
Heat & other forms of energy
Heat added at a constant volume of a gas is used to:
To increase its internal energy
When heat is given to gas is an isobaric process then;
➡The work is done by the gas
➡Internal Energy of the gas increases
If the volume of a gas is decreased by 10% during the isothermal process then its pressure will:
Increase by 11.11%
During this process the volume of the system remains constant:
Isochoric
A gas does 10J of external work in an adiabatic process while expanding, then the change in internal energy is;
-10 J
Q = ΔU + W
During the adiabatic expansion of 2 moles of a gas, the internal energy of the gas is found to decrease by 2 joules, the work done during the process on the gas will be equal to;
2J
Q = ΔU + W
Starting with the same initial conditions, an ideal gas expands from volume V1 to V2 in three different ways. The work done by the gas is W1 if the process is purely isothermal. W2 if purely isobaric and W3 if purely adiabatic then;
W2>W1>W3
Cp - Cv value, find if 3 moels of gas give:
3R
A valid unit of specific heat capacity is;
Jkg-1K-1
If 1 mole of monoatomic gas γ=5/3 is mixed with 1 mole of diatomic gas γ=7/5. What is the value of γ for the mxiture?
1.5
Find the internal energy of the system containing 2 moles of oxygen and 4 moles of argon:
11RT
If the energy required to raise the temperature of 10°C is 20J at constant volume then how much energy is required to raise the same temperature at constant pressure?
40 J
Find the molar-specific heat capacity of diatomic gas which work done is Q/4 if heat is given to the system>
10/3 R
The internal energy of one gram of helium at 100K and one atmospheric pressure is;
300J
310 J of heat is required to raise the temperature of 2 moels of an ideal gas at constant pressure from 25°C to 35°C. The amount of heat energy required to raise the temperature of gas through the same range at constant volume is:
143J
The first law of thermodynamics is related to:
Law of conservation of energy
Cv/ Cp is equal to:
1/γ
When Cp = 20 J/kg k and 1 mole of gas is present then Cv is?
4.36 J/kgk
1 gamma for poly atomic gas is;
1.29
Which one is true about Cv and Cp?
Cp > Cv
Which of the following is incorrect?
➡Cp - Cv = R❌
➡Cp = R - Cv❌
➡Cp/Cv = R✅
➡ R + Cp = Cv❌
If the pressure of diatomic gas varies as P = aV2 then its heat capacity will:
17 R/6
Specific heat capacity in terms of heat capacity is;
C/m
At 0° K which of the following properties of gas will be zero
Kinetic Energy
What will be changed in internal energy when work is done by the system is 50KJ heat absorbed is 40 KJ.
-10KJ
Gas laws are applicable to:
Gases alone and not to vapours
An ideal gas as compared to a real gas at very high pressure occupies:
More volume
The unit of pressure in the S.I Unit is
Pascal
Thermodynamics does not consider:
Time Factor
A system which can neither exchange matter nor energy with the surroundings is called:
Isolated system
Absolute zero temperature is taken as;
-273°C
In the isothermal process:
Temperature is constant
Absolute zero pressure will be;
When molecule moment o system is zero
If the volume of a gas is held constant and we increase its temperature then:
Its pressure rises
For a gas obeying Boyles’s law, if the pressure is doubled the volume becomes:
One half
If Cp = 34.4 J/mol K and the value of R is 8.314 then:
Cv = 26.1 J/mol K
The difference between the principal specific heats of nitrogen is 300 J/kg-K and the ratio of the two specific heats is 1.4 then:
Cp = 1050 J/kg-K
The equation of state corresponding to 8 g of O2 is:
PV = RT/4
Cv of gas is 8 calK-1mole-1. Find Cp/Cv. Assume R = 2calK-1mol-1
1.25
100g of water is heated from 30°C to 50°C. Ignoring the slight expansion of the water, the change in its internal energy is:
(specific heat of water is 4184 J kg-1 K-1)
8.4 kJ
When an ideal diatomic gas is heated at constant pressure, the fraction of the heat energy supplied that increases the internal energy of the gas is:
5/7
How much heat is needed to raise the temperature of 100 g of H2O from 22°C to 98°C?
32 kJ
A 500-gram cube of lead is heated from 25°C to 75°C. How much energy was required to heat the lead? The specific heat of lead is 0.129 J/g°C
3225 J
A closed container contains an ideal gas. Which of the following changes will result in a decrease in temperature?
➡Volume increase
➡Temperture decrease
The efficiency of the heat engine can be defined as:
1 - Q2/Q1
For an isothermal process, the first law of thermodynamics can be written as:
Heat absorbed = work done by the system
Boltzmann’s constant k is defined as:
R/N A
A liquid has mass m and specific heat capacity c. The rate of change in temperature of the liquid is R. What is the rate at which heat is transferred from the liquid?
Rmc
100W heater is used to heat 500g of water from 20°C to 50°C. How long should the heater be switched on?
The specific heat capacity of water is 4.2 J/gC
630 sec
The energy input to an engine is 60 J, and the work it performs is 15J. What is its thermal efficiency?
0.25
Which of the following is equivalent to a temperature of 150K?
-123°C
A monoatomic ideal gas is thermally insulated, so no heat can flow between it and its surroundings. Is it possible for the temperature of the gas to rise?
Yes
➡The temperature can rise if work is done on the gas
Some ice, at its melting point, is added to m kg of water at an initial temperature of 290K. if c is the specific heat capacity o water and L is the latent heat of fusion of ice. Ice melts completely. The final temperature of the water is 273 K. What is the minimum mass of ice that is required?
17 mc/L
Under what conditions of temperature and pressure do a real gas approximate to an ideal gas?
➡Pressure Low
➡Temperatre High
In which process the net work done is zero>
Isochoric
Internal energy remains the same throughout the process in:
Isothermal Process
An ideal gas is compressed to half of its initial volume. Which of these processes would result in maximum work done>
Adiabatic
If the system changes from a state P1 V1 to P2V2 by two paths then the quantity which remains unchanged is:
ΔQ -ΔW
An ideal reversible heat engine is 1 efficient only if:
The cold reservoir is at 0K
The efficiency of the heat engine in terms of temeprature of reservoir and sink is defined as:
1 - T1/T2
According to the first law of thermodynamics;
ΔQ = ΔU + ΔW
Which of the following is a thermodynamic coordinate?
R
When heat is given to the isobaric process then;
➡Work is done by the gas
➡Internal Energy of gas decreases
If N is the number of molecules of gas in a container. Then a number of moles can be calculated as:
N + NA
100 W heater is used to melt 50g of ice at 0°C. How long should the heater switch on?
Specific heat latent heat of fusion of ice is 334 J/g.
16.7 min
The sum of all forms of molecular energies (kinetic and potential) of a substance is termed as its:
Potential Energy
When an ideal gas of constant mass is heated in a container of fixed volume. What is the reason for the increase in pressure of the gas?
Average force per impact at the container wall increases
The isothermal process can be defined as:
PV = Constant
Which of the following process is irreversible?
A chemical explosion
During an adiabatic process, the pressure of the gas is found to be proportional to the fourth power of temperature. The ideal gas would be;
CH2
Temperature is defined by:
Zeroth Law of thermodynamics
The internal energy of the system depends on:
The path from the initial to the final state
The initial mass of water, at its boiling point, is 0.8 kg. 4 kW of the heater is used to boil it completely. Assuming the specific latent heat of vaporization of water in 2MJ/kg. What is the time taken to vaporize all the water?
400sec
100 W heater is used for 5 minutes to heat 500g of water. What is the change in the temperature of the water which is heated?
The specific heat capacity of water is 4.2 J/gC
14°C
100 W heater is used for 5 minutes to heat some water from 20°C to 50°C. What is the mass of water which is heated?
The specific heat capacity of water is 4.2 J/gC
240 g
A car of mass M is moving with speed v. The brake of mass m and specific heat capacity c is used to stop the car. If half of the kinetic energy of the car is absorbed by the brake, then what is the increase in temperature of the brake:
Mv2/4mc
If ΔU and ΔW represent internal energy and work done which is true?
ΔU = -ΔW in an adiabaic process
The P-V diagram of a diatomic gas is a straight line passing through the origin. What is the molar heat capacity of the gas in the process?
3R
What does the constant n represent in the equation of state for an ideal gas PV nRT?
Number of moles of the gas
If P=Po and V=Vo gas expands isothermally to P=3Po, then the volume is;
Vo/3
Which of the terms is related to thermodynamics?
➡System
➡Boudnary
➡Surrounding
The amount of heat supplied to 0.02 kg of nitrogen to raise its temperature by 45° is;
934J
What is the internal energy change in a system that has absorbed 800J of heat and work done is 500J?
300J
“The heat required to raise the temperature of one mole of the substance through 1K” is called:
Molar specific heat
Which of the following is not an assumption o the kinetic model of an ideal gas?
➡Collisions between molecules and walls of the container are elastic❌
➡The duration of collision between molecules is very short❌
➡All particles of gas have the same speed✅
➡All particles of gas have same mass❌
The thermodynamics process during which the pressure is kept constant, is called;
Isobaric
An ideal gas has a volume of 20ml, a temperature of 10°C and pressure of 100kPa. The volume of the gas is reduced to 10ml and the temperature is raised to 20°C. What is the new pressure of the gas?
207 kPa
Two identical gases expand i) isothermally ii) adiabatically. Work done is more in:
Isothermal Process
In which of the following processes the heat is neither absorbed nor released by a system?
Adiabatic
A heater is used for 5 minutes to heat 500g of water from 20°C to 50°C. What is the power of the heater?
The specific heat capacity of water is 4.2 J/gC
1260 W
Which of the following is equivalent to a temperature -50°C?
223K
In Boyle’s Law, which quantity is constant
T
A gas expands from V1 to V2. The amount of work done is greatest in:
Isobaric
If heat given is 6kcal and work done is 6kJ, then internal energy is;
19.1 kJ
A container is filled with oxygen and helium at the same temperature. The molar mass of oxygen is 32 g/mol and that of helium is 4 g/mol. What is the ratio:
average speed o oxygen molecules _______ average speed o helium molecules?
1/√8
How much energy is required to raise the temperature of 5.00 kg of lead from 20.0°C to its melting point of 327°C? The specific heat of lead is 128 J/kg°C
1.96 x 10^5 J
In thermodynamics first law is related with;
Energy conservation
In the VT diagram slope of the curve is:
nR/P
“The amount of heat transfer required to raise the temperature of one mole of the gas through 1K at constant pressure is called:
The molar-specific heat at constant pressure
The energy input to an engine is 4.00 times greater than the work it performs. What fraction of the energy input is expelled to the cold reservoir?
0.75
100 W heater is switched on for 5 minutes to melt ice. What is the mass of ice that melts at 0°C? Specific latent heat of fusion of ice is 334j/g
90 g
In thermodynamics zeroth law is related with:
Therma Equilibrium
The value of universal gas, R, the constant is:
8.314 J/mol/K
Which of these is constant in the adiabatic process:
➡Total Heat
➡Entropy
Which of the following is not an assumption of the kinetic model of an ideal gas?
The kinetic energy of a given particle is the same
A cycle tyre bursting suddenly is an example of:
Adiabatic Process
300 W heater is used to boil 500g of water at 100°C. How long should the heater switch on? Specific latent heat of vaporization of water is 2230 J/g.
62 mins
An ideal gas o N molecule is enclosed in a container at a constant pressure of P. The graph between the volume of gas and its absolute temperature is a straight line. What is the gradient of the graph?
Nk/P
The efficiency of the diesel engine is:
35% to 40%
The isothermal system has a constant:
Temperature
When no heat enters or leaves the system, it is called:
Adiabatic
The engine is supposed to work between 727°C and 227°C, the maximum possible efficiency is:
1/2
The molar mass of water is:
0.018 kg/mol
An ideal gas at 15.5°C and pressure of 1.72x 10^5 Pa occupies a volume of 2.81 m3. How many moles of gas are present
201 mol
One kcal =
4180 K
If 1 mole of an ideal gas is heated at a constant volume so that its temperature rises by ΔT, then the first law of thermodynamics can be written as:
ΔU = CvΔT
A gas expands 0.25m3 at a constant pressure of 10^3 N/m2 then work done is;
250 joules
For ideal polyatomic gas molar specific heat is equal to;
24.9 J/mol.K
All changes which occur suddenly or which involve friction or dissipation of energy through conduction, convection or radiation are:
Irreversible Changes
Which of the following is equivalent to a temperature of -15°C?
123K
Which statement is incorrect?
➡In an isobaric process ΔP=0❌
➡In an isothermal process ΔT=0❌
➡In an isochoric process ΔW=0❌
➡In an isothermal process ΔQ=0✅
The value of a triple point of water is;
273.16K
Under a cyclic path, internal energy after the complete cycle is the same as:
Initial internal energy
Initial pressure and volume are P and V respectively. First, it expanded isothermally to 4V and then compressed adiabatically to volume V, the final pressure is;
1P
A reversible Carnot engine converts 1/6th of heat into input work then the efficiency of the engine is:
0.166
Specific heat o water is:
4180 J/kg.K
Two objects, with different sizes, masses, and temperatures are placed in thermal contact. In which direction does the energy travel?
Energy travels from the object at a higher temperature to the object at a lower temperature
Area of PV diagram gives:
Work done
The first law of thermodynamics is a special case of;
Conservation of energy
Work done in an adiabatic process in a gas depends upon;
Change in temperature
The energy input to an engine is 60J, and the work it performs is 15J. What reaction of the energy input is expelled to the cold reservoir?
75%
The energy input to an engine is 4.00 times greater than the work it performs. What is its thermal efficiency?
0.25
The heat reservoir is a ___ temperature bath.
Constant
The slope of the adiabatic(ks) and isothermal(kt) curve is related as:
ks = γkt
If the heat is absorbed is 10J and Work done is 5J, then the change in internal energy is;
5J
A sample of 0.1 g of water at 100°C and normal pressure requires 54 cal of heat energy to convert to steam at 100°C. If the volume of the steam produced is 167.1°C, the change in internal energy of the sample is:
208.6 kJ
A monoatomic gas at pressure P and Volume V expands isothermally to volume 2V and then adiabatically to volume 16V. The final pressure is:
P/64
When the temperature of the system does not change, it is called:
Isothermal
A fraction of internal energy is due to molecular vibration, which is different in different states of matter. Which of the following gives the correct order of a fraction of internal energy due to molecular vibration?
Solid>Liquid>Gas
A 1.0 kW heater supplies energy to a liquid of mass 1kg. The temperature of the liquid changes by 80K in a time of 400s. The specific heat capacity of the liquid is 4.0 kJ/kg.K. What is the average power lost by the liquid?
800
For an adiabatic process, the first law of thermodynamics can be written as:
Work done by the system = Decrease in internal energy of a system
The adiabatic process can be defined as:
PV^γ = Constant
During an adiabatic process pressure of a gas is found to be proportional to the cube of its temperature. The ratio of Cp/Cv is:
3/2
A reversible Carnot engine converts 1/6th of heat into input work. When the temperature o sink is reduced to 62°C, then efficiency is doubled the temperature of the source and sink is;
99°C, 37°C
The sum of all forms of molecular energies of a substance is termed as its:
Internal energy
Specific latent heat of fusion of ice is 334 J/g. How much energy decreases by 300J? If at the same time 120J of work is done on the system, find the heat lost by the system.
-420 J
An ideal reversible heat engine has:
Highest efficiency
What does the constant n represent in the equation of state for an ideal gas PV=nRT?
Number of moles o the gas
Which of the following process is reversible?
Isothermal Compression
The efficiency of heat engine in terms of the temperature of reservoir and sink is defined as;
1 - T1/T2
Which of the terms is related to thermodynamics?
➡System
➡Boundary
➡Surrounding
The value of universal gas, R, constant is;
8.3214 J/mol x K
Under what conditions of density and pressure does a real gas approximate to an ideal gas?
➡Density low
➡Pressure low
Which one of the following is not the unit of heat?
Watt
A heat engine performs 100J of work and at the same time rejects 400J of heat energy to the cold reservoirs. What is the efficiency of the engine?
20%
The energy input to an engine is 4.00 times greater than the work it performs. What fraction of the energy input is expelled to the cold reservoir?
0.75
The value of universal gas, R, constant is;
8.314 J/mol x K
A 500 W electric heater is used to heat 1 kg of water without energy losses. The specific heat capacity of water is 4.2 kJ kg K. What is the time taken to heat the water from 25°C to 75°C?
42 seconds
A reversible engine works between two temperatures whose difference is 100°C. If it absorbs 746J of heat from the source and rejects 546J to the sink, calculate the temperature of the source and the sink.
100°C, 0°C
If for a gas (ΔW=0, ΔQ<0) then;
Pressure decreases
Which of the following is not an assumption of the kinetic model of an ideal gas?
Mileculessufer negligible momentum change during wall collisions
A monoatomic gas is heated from temperatures T1 and T2 under two different conditions at (i)Constant Volume (ii) Constant Pressure. So change in U is:
Same for both
Work done in an adiabatic process of gas from T1 to T2 is:
nR/γ-1 (T1-T2)
The increase in temperature of the object is an indication of;
Increase in internal energy
100 W heater is used for 5 minutes to heat 500g of water. What is the change in the temperature of the water?
The specific heat capacity of water is 4.2 j/gC.
14°C
if 110J heat is added to the system and 40J work is done, then the amount o work done is;
70J
An adiabatic change is the one in which:
No heat is added to or taken out of a system
Internal energy remains the same throughout the process in:
Isothermal Process
The sum of all forms of molecular energies of a substance is termed as its:
Internal energy
Qual masses of paraffin and water are mixed in a container of negligible thermal capacity. The initial temperature of the water is 80°C and that of paraffin is 20°. The final temperature of the mixture is:
50°C
For a reversible process, a necessary condition is;
The process must be quasistatic
If the system goes from two different paths to the same final state, then Q1 and W1 and Q2 and W2 are heat absorbed and work done then:
Q1 - W1 = Q2 - W2
A liquid has sepcific heat capcity c. The rate of change in temperature of the liquid is R. The rate at which what is transferred from the liquid is P. What is the mass of the liquid?
P/cR
The energy input to an engine is 60J, and the work it performs is 15J. What it’s the fraction of the energy input is expelled to the cold reservoir?
75%
A temperature of 162°C is equivalent to what temperature in Kelvins?
425K
When an ideal gas of constant mass is heated in a container of fixed volume. What is the reason for the increase in pressure of the gas?
Average force per impact at the container wall increases
A common material for cushioning objects in packages is made by trapping bubbles of air between sheets of plastic. Is this material more effective at keeping the contents of the package from moving around inside the package?
A hot day
Which of this is constant in the isothermal process?
Internal Energy
Work done in an isobaric process is given by:
PΔV
The energy input to an engine is 4.00 times greater than the work it performs. What fraction of the energy input is expelled to the cold reservoir?
0.75
How much energy is required to raise the temperature of 5.00 kg of lead from 20°C to its melting point of 327°C? The specific heat of lead is 128 J/kg.
1.96 x 10^5 J
Under which conditions, areal gas approximate to an ideal gas?
Pressure = Low Density = High
A refrigerator operates for a certain time, and the work done by the electrical energy during this time is W=1000J. What can be said about the heat delivered to the room containing the refrigerator?
The heat delivered to the room is greater than 1000J
The first law of thermodynamics states:
Heat is the form of energy
If the temperature of a reservoir of Carnot engine working with efficiency 70% is 1000K, then the temperature of the sink is:
300K
A monoatomic gas is supplied to heat Q very slowly keeping the pressure constant. The work done by the gas is:
2Q/5
The energy input to an engine is 60J, and the work it performs is 15J. What is its thermal efficiency?
0.25
What does the constant N represent in the equation o state for an ideal gas PV=NkT
Number of molecules of gas
Work done by bas, pressure and change in volume are related as:
W=PΔV
If Q, E and W are the parameters in the cyclic process then:
E=0
An ideal gas at 15.5°C and pressure of 1.72 x 10^5 Pa occupies a volume of 2.81 m3. If the volume is raised to 4.16 m3 and the temperature is raised to 28.2°C, what will be the pressure of the gas?
1.21 x 10^5 Pa
Which of the following is an example of an isothermal process?
Slow compression or expansion of a gas
The work done can also be calculated by:
Area of the curve under the P-V graph
What does the constant N represent in the equation of state for an ideal gas PV=NkT?
Number of molecules as
Under which conditions, does a real gas approximate an ideal gas?
Pressure = Low Density = Low
A fixed mass of gas undergoes isochoric (isovolumetric) change. As a result, the pressure of the gas has increased . Which of the following is true about the gas?
Internal energy= Increase the direction of transfer of thermal energy= Absorbed by the gas
Which of the following cannot determine the state of the thermodynamic system?
P and R
In adiabatic expansion:
ΔU = negative
What is the internal energy change in a system that has absorbed 800J of heat and work done is 500J?
300J
In thermodynamics, zeroth law is related with:
Thermal equilibrium
When we heat a substance, the energy associated with its atoms or molecules is increased. It means:
Heat is converted to internal energy
Two containers hold na ideal gas at the same temperature and pressure. Both containers hold the same type of gas, but container B has twice the volume the container.
What is the average translational kinetic energy per molecule in container B?
Half that of container
A cyclic path is one in which the initial state is equal to;
Final state
If 1.002 x 10^6 if thermal energy is required to melt some ice at its melting point, what is the mass of ice that melts? Specific latent heat of fusion of ice is 334 J/g
3 kg
The turbine in a steam power plant takes steam from a boiler at 427°C and exhausts into a low, temperature reservoir at 77°C. What is the maximum possible efficiency?
50%
Which of the following statement is not true about heat engines?
➡All real engines are less efficient than the Carnot engine❌
➡All real engines are less efficient due to friction and heat losses❌
➡Efficiency of Carnot engine working between same two temperatures, depends on the nature of working substance✅
➡The larger the temperature difference between two reservoirs, the greater the efficiency❌
The internal energy change in a system that has absorbed 2kcal of heat and done 500J of work is;
7900J
The molar-specific heat of a diatomic gas is measured at constant volume and found to be 29.1 J/mol K. What are the types of energy that are contributing to the molar-specific heat?
➡Translation
➡Rotation
➡Vibrational
In which process the net work done is zero?
Free Expansion
Which of the following is an assumption of the kinetic model of an ideal gas?
The collision between particles is elastic
During adiabatic expansion internal energy decreases by 2J, then work done in this process is;
2J
Two containers X and Y are filled with an ideal gas. X has 1 mole of gas and Y has 2 moles of gas. The volume of Y is four times that of X. Pressure in Y is half that in X. What is the temperature of the gas in Y _____ temperature of the gas in X
1
An ideal gas at 15.5°C and a pressure of 1.72 x 10^5 Pa occupy a volume of 2.81 m3. How many moles o gas are resent?
201 mole
An ideal gas at 15.5°C and a pressure of 1.72 x 10^5 Pa occupy a volume of 2.81 m3. If the volume is raised to 4.16 m3 and the temperature is raised to 28.2°C, what will be the pressure of the gas?
1.21 x 10^5 Pa
What is the factor upon which the change in internal energy of an ideal gas depends?
Change in temperature
Change in internal energy of a gas depends upon temperature
The amount of heat required to raise the temperature o 1kg of substance through 1 K is called:
Specific heat Capacity
I one mole of an ideal gas is heated at constant pressure, then the first law of thermodynamics can be written as;
CpΔT = CvΔT + PΔV
If Cv=5/2 R, Cp will be;
7/2 R
The amount of heat required to raise the temperature of 10 moles of water from 70K to 80 K
(molar heat capacity of water is 75.24 J)
7524J
The sum of all forms of molecular energies of a substance is termed as;
Internal energy
In which process, the entire heat supplied to the gas is converted to internal energy?
Isochoric Process
The internal energy of a system during an isothermal process:
Remain Constant
(T∝U)
➡T=Constant, U=Constant
In a certain process, 40J of heat energy is supplied to a system and at the same time, 150J of work is done by the system. The increase in internal energy of the system is:
250J
The rapid escape of air from a burst tyre is an example of :
Adiabatic
Cp - Cv value, find 3 moles of gas gives:
3R
Examples of first law of thermodynamcis are:
➡Working of bicycle pump
➡Human metabolism
➡Brakes applied by an automobile
The graphical line of isochoric process is parallel to the:
Pressure axis
In isothermal process which of the following is not true?
No heat enters or leaves the system
First law of thermodynamics for an adiabatic process is:
W = -ΔU
The rapid expansion and compression of air thorugh which a sound wave is passing, obeys:
Adiabatic Process
If the volume of the gas is to be increased by 4 times , then:
A constant P the temeprature must be increased by four times
The cloud formation is the example of;
Adiabtatic Process
In realtion PV^γ = constant the γ is given by:
Cp/Cv
Compressed air coming out of punctured football becomes cooler because of:
Isothermal Expansion
Find the change in internal energy of the system when a system absorbs 2 kilocalorie of heat and at the same time does 500 joule of work:
7900J
In a thermodynamic system working susbtance is ideal gas, its internal energy is in the fomr of :
Kinetic Energy only
Which of the following statement is correct for any thermodynamic system?
Internal energy and entropy are state function
If heat given to a system is 6 kcal and work done is 6kJ. The change in internal energy is:
19.1 kJ
the amount of heat required to raise the temeprature of one kg of susbtance thorugh 1 K is called:
Specific Heat
For 1 mole of gas the relation PΔV =
RΔT
A gas, for which γ is 4/3, is heated at constant pressure. The percentage of heat supplied used for external work is:
25%
The diference between the molar specific heat at cosntant pressure and volume is called:
Universal Gas Constant
For mono-atomic gas Cv = 3R/2, therefore γ for this gas is:
5/3
The unit of moalr specific heat is same as that of:
Molar ideal gas constant
110J of heat is added to a gaseous system, whose internal energy change is 40J. then the amount of external work done is:
70J
Which of the following can not determine the state of thermodynamic system
Any one of pressure, volume or temperature
The specific heats at constant pressure is greater than that of the gas at cosntant volume because:
at constant pressure work is done in expanding the gas
If the amount of heat given to a system be 35joules and the amount of work done by the system be 15 joules, then the change in the internal energy of the system is:
20 joules
The value of universal gas cosntant R is:
8.314 J mol-1 K-1
Which of the following possess maximum root mean square velocity at same temperature?
Hydrogen
The average K.E of hydrogen molecules at 300K is E. At same temerature K.E of oxygen molecuels will be:
E
Which of the following is not a state function fo a ssytem?
Heat
The equation of state for 5 g of oxygen at a pressure P and Temperature T, when occupying a volume V , will be:
PV = (5/32)RT
Which of teh following is expression of mean square speed of “N” gas molecuels contained in a cylinder?
V1^2 +V2^2 +Vn^2/N
A vessel contains 1 mole of O2 at temperature T. The pressure Is P. An identical vessel containing 1 mole o He gas at a temperature 2T has ap ressure.
2P
In the mass of all moelcuels of a gas are halved and their speed is doubled, then the ratio of their initial and final pressure is;
1:2
For mono atomic gas Cv = 3/2 R value of Cp is:
5/2 R
The temperature of a gas is raised from 27°C to 927°C. The root mean square speed is:
Gets doubled
The temperature of a gas is increased from 27°C to 127°C. The ratio of its mean kinetic energies will be:
3/4
The volume of a gas will be double of what it is at 0°C at:
273°C
The speeds of 5 molecuels of gas are as follows: 2,3,4,5,6
The root mean square speed for these molecuels is:
4.24 m/s
Pressure of a gas at constant volume is proportional to:
Kinetic Energy of molecules
Two identical sample of a gas are allowed to expand (i) isothermally (ii) adiabatically. Work done is:
More in the isothermal process
Mean square velocity of five moelcuels of velocities 2 m/s, 3m/s, 4 m/s, 5m/s and 6 m/s is:
18 m2/s2
A gas is taken in a sealed container at 300K. It is heated at cosntatn volume to a temperature 600K. The mean K.E of its molecules is:
Doubled
The mean kinetic enrgy of one gram-mole of a perfect gas at absolute temeprature T is:
3/2 RT
For hydrogen gas Cp-Cv = a and for oxygen gas Cp-Cv=b, so that relation between a and b is given by:
a= b
According to kinetic theory of gases at absolute zero temeprature
Molecuels motion stops
If Cp-Cv = R and Cp/Cv = γ, then which relation is correct
Cv = R/γ -1
If a cylinder containing a gas at high pressure explodes, the gas undergoes:
➡Irreversible adiabatic change
➡Fall of temeprature
Which of the followin is relation for V(r.m.s):
➡√EP/ρ
➡√3RT/M
➡√3kT/M
What thermodynamic temeprature is equivalent to 501.85°C?
775.00K
Which is called internal energy of an ideal gas?
Translational Kinetic energy
Cloud formation in atmosphere is an exampe of :
Adiabatic Process
The triple point of water is:
273.16K
The temeprature of a gas is increased from 27°C to 127°C. The ratio of its mean kinetic energies will be:
3/4
110 Joules of heat are added to a gaseous system, whose internal energy is 40J. The amount of external work done is:
70J
A system doe 600J of work at the same time has its internal energy increased by 320J. How much heat is suplied?
920J
Gas molecules of different masses in the same container have the same translational kinetic energy. Which is direclty proportional to:
Absolute Temeprature
Average translational kinetic energy per molecule of an ideal gas is given by:
3RT/2NA
The internal nergy of 1 mole of an ideal gas depends upon:
Only tmeprature
The average kinetic energy of hydrogen moelcules at 300K is E. At the same temperature, the average kinetic energy of oxygen moelcules will be:
E
If Q is amount of heat added to a system and W is work done by the system, then change in internal nergy can be defined as:
Q-W
The rms speed of moelcuels of a gas depends upon:
➡Pressure of gas
➡Temeprature of gas
➡Density of gas
Mass (m ) of one molecule of a gas can be written as:
Molecular Mass/NA
If the volume of a gas is held constant and we increase its temperature then:
Its Pressure rises
At constant pressure the volume of the given mass of a gas is V at temperature T. At what temeprature volume of the gas will be 4V:
4T
Which one of the expression is correct for the molar volume V of an ideal gas:
RT/P
As Cp-Cv =R shows that Cp> Cv. What is also true?
ΔUp = ΔUv
According to the first law of thermodynamcis applied to a gas, the increase in the internal nergy during any process:
Equals the heat input plus the work done on the gas
