In case of compression of one kg of air, the work done will be the least, when the value of polytropic index 'n' is (A) 1 (B) 1.4 (C) 1.5 (D) Y = Cp/Cv

In case of compression of one kg of air, the work done will be the least, when the value of polytropic index 'n' is
(A) 1
(B) 1.4
(C) 1.5
(D) Y = Cp/Cv
by

1 Answer

Answer :

A) 1
by

Related questions

In the equation, PVn = constant, if the value of n is in between 1 and y (i.e. Cp/Cv), then it represents a reversible __________ process. (A) Isometric (B) Polytropic (C) Isentropic (D) Isobaric

Description : In the equation, PVn = constant, if the value of n is in between 1 and y (i.e. Cp/Cv), then it represents a reversible __________ process. (A) Isometric (B) Polytropic (C) Isentropic (D) Isobaric

Last Answer : (B) Polytropic

In the equation PVn = constant, if the value of n = y = Cp/Cv, then it represents a reversible __________ process. (A) Isothermal (B) Adiabatic (C) Isentropic (D) Polytropic

Description : In the equation PVn = constant, if the value of n = y = Cp/Cv, then it represents a reversible __________ process. (A) Isothermal (B) Adiabatic (C) Isentropic (D) Polytropic

Last Answer : (C) Isentropic

In case of steady flow compression polytropic process (PVn = constant), the work done on air is the lowest, when (A) n = y = 1.4 (B) n = 0 (C) n = 1 (D) n = 1.66

Description : In case of steady flow compression polytropic process (PVn = constant), the work done on air is the lowest, when (A) n = y = 1.4 (B) n = 0 (C) n = 1 (D) n = 1.66

Last Answer : (C) n = 1

Air enters an adiabatic compressor at 300K. The exit temperature for a compression ratio of 3, assuming air to be an ideal gas (Y = Cp/Cv = 7/5) and the process to be reversible, is (A) 300 × (32/7) (B) 300 × (33/5) (C) 300 × (333/7) (D) 300 × (35/7)

Description : Air enters an adiabatic compressor at 300K. The exit temperature for a compression ratio of 3, assuming air to be an ideal gas (Y = Cp/Cv = 7/5) and the process to be reversible, is (A) 300 × (32/7) (B) 300 × (33/5) (C) 300 × (333/7) (D) 300 × (35/7)

Last Answer : A) 300 × (32/7)

The value of Cp & Cv respectively for monatomic gases in Kcal/kg Mole.°K are (A) 5 & 3 (B) 3.987 & 1.987 (C) 1.987 & 0.66 (D) 0.66 & 1.987

Description : The value of Cp & Cv respectively for monatomic gases in Kcal/kg Mole.°K are (A) 5 & 3 (B) 3.987 & 1.987 (C) 1.987 & 0.66 (D) 0.66 & 1.987

Last Answer : A) 5 & 3

The value of y = cp/cv. at < 500°C for air & most common gases can be safely assumed to be (A) 0.8 (B) 1 (C) 1.4 (D) 1.8

Description : The value of y = cp/cv. at < 500°C for air & most common gases can be safely assumed to be (A) 0.8 (B) 1 (C) 1.4 (D) 1.8

Last Answer : Option C

In a single stage reciprocating air compressor, the work done on air to compressor is from suction pressure to delivery pressure will be minimum when the compression is A. Isothermal process B. Adiabatic process C. Polytropic process D. Constant pressure process.

Description : In a single stage reciprocating air compressor, the work done on air to compressor is from suction pressure to delivery pressure will be minimum when the compression is A. Isothermal process B. Adiabatic process C. Polytropic process D. Constant pressure process.

Last Answer : ANSWER : A

One kg of gas occupying 0.1m^3 at pressure of 14 bar is expanded at constant pressure to 0.2m^3. Determine an initial and final temperature of gas. Take Cp=1.008KJ/KgK, Cv =0.72KJ/KgK.

Description : One kg of gas occupying 0.1m^3 at pressure of 14 bar is expanded at constant pressure to 0.2m^3. Determine an initial and final temperature of gas. Take Cp=1.008KJ/KgK, Cv =0.72KJ/KgK.

Last Answer : V1=0.1m^3 V2=0.2 m^3 P1=P2=14 bar Cp=1.008 KJ/KgK Cv=0.72 KJ/KgK R=Cp-Cv R=1.008-0.72 R=0.288KJ/KgK Characteristic gas equation,  P1V1=mRT1 14*10^5*0.1=1*288*T1 T1=486.11K For constant pressure process, V1/T1=V2/T2 0.1/486.11=0.2/T2 T2=972.22K

y = specific heat ratio of an ideal gas is equal to (A) Cp/Cv (B) Cp/(CP-R) (C) 1 + (R/CV) (D) All (A), (B) and (C)

Description : y = specific heat ratio of an ideal gas is equal to (A) Cp/Cv (B) Cp/(CP-R) (C) 1 + (R/CV) (D) All (A), (B) and (C)

Last Answer : D) All (A), (B) and (C)

On a P-V diagram of an ideal gas, suppose a reversible adiabatic line intersects a reversible isothermal line at point A. Then at a point A, the slope of the reversible adiabatic line (∂P/∂V)s and the slope of the reversible isothermal line (∂P/∂V)T are related as (where, y = Cp/Cv) (A) (∂P/∂V)S = (∂P/∂V)T (B) (∂P/∂V)S = [(∂P/∂V)T]Y (C) (∂P/∂V)S = y(∂P/∂V)T (D) (∂P/∂V)S = 1/y(∂P/∂V)T

Description : On a P-V diagram of an ideal gas, suppose a reversible adiabatic line intersects a reversible isothermal line at point A. Then at a point A, the slope of the reversible adiabatic line (∂P/∂V)s and the slope of the reversible isothermal line ... Y (C) (∂P/∂V)S = y(∂P/∂V)T (D) (∂P/∂V)S = 1/y(∂P/∂V)T

Last Answer : (C) (∂P/∂V)S = y(∂P/∂V)T

Velocity of a gas in sound is not proportional to (where, T = Absolute temperature of the gas. P = Absolute pressure of the gas. y = Ratio of specific heats (Cp/Cv) ρ = specific weight of the gas) (A) √T (B) 1/√P (C) √y (D) 1/√ρ

Description : Velocity of a gas in sound is not proportional to (where, T = Absolute temperature of the gas. P = Absolute pressure of the gas. y = Ratio of specific heats (Cp/Cv) ρ = specific weight of the gas) (A) √T (B) 1/√P (C) √y (D) 1/√ρ

Last Answer : (B) 1/√P

The value of specific heat at constant pressure (cp) is __________ that of at constant volume (cv).  A. less than  B. equal to  C. more than

Description : The value of specific heat at constant pressure (cp) is __________ that of at constant volume (cv).  A. less than  B. equal to  C. more than

Last Answer : Answer: C

Cp /Cv is termed as (A) Adiabatic constant (B) Mach number (C) Weber number (D) Prandtl number

Description : Cp /Cv is termed as (A) Adiabatic constant (B) Mach number (C) Weber number (D) Prandtl number

Last Answer : (A) Adiabatic constan

In a P-V diagram (for an ideal gas), an isothermal curve will coincide within adiabatic curve (through a point), when (A) Cp < Cv (B) Cp = Cv (C) Cp > Cv (D) C ≥ Cv

Description : In a P-V diagram (for an ideal gas), an isothermal curve will coincide within adiabatic curve (through a point), when (A) Cp < Cv (B) Cp = Cv (C) Cp > Cv (D) C ≥ Cv

Last Answer : (B) Cp = Cv

(1/V) (∂V/∂T)Pis the mathematical expression (A) Joule-Thomson co-efficient (B) Specific heat at constant pressure (Cp) (C) co-efficient of thermal expansion (D) Specific heat at constant volume (CV)

Description : (1/V) (∂V/∂T)Pis the mathematical expression (A) Joule-Thomson co-efficient (B) Specific heat at constant pressure (Cp) (C) co-efficient of thermal expansion (D) Specific heat at constant volume (CV)

Last Answer : (C) co-efficient of thermal expansion

If the molar heat capacities (Cp or Cv) of the reactants and products of a chemical reaction are identical, then, with the increase in temperature, the heat of reaction will (A) Increase (B) Decrease (C) Remain unaltered (D) Increase or decrease; depends on the particular reaction

Description : If the molar heat capacities (Cp or Cv) of the reactants and products of a chemical reaction are identical, then, with the increase in temperature, the heat of reaction will (A) Increase (B) Decrease (C) Remain unaltered (D) Increase or decrease; depends on the particular reaction

Last Answer : (C) Remain unaltered

For a constant pressure reversible process, the enthalpy change (ΔH) of the system is (A) Cv.dT (B) Cp.dT (C) ∫ Cp.dT (D) ∫ Cv.dT

Description : For a constant pressure reversible process, the enthalpy change (ΔH) of the system is (A) Cv.dT (B) Cp.dT (C) ∫ Cp.dT (D) ∫ Cv.dT

Last Answer : (C) ∫ Cp.dT

PVγ = Constant (where, γ = Cp/Cv) is valid for a/an __________ process. (A) Isothermal (B) Isentropic (C) Isobaric (D) Adiabatic

Description : PVγ = Constant (where, γ = Cp/Cv) is valid for a/an __________ process. (A) Isothermal (B) Isentropic (C) Isobaric (D) Adiabatic

Last Answer : (D) Adiabatic

(∂T/∂P)H is the mathematical expression for (A) Specific heat at constant pressure (Cp) (B) Specific heat at constant volume (Cv) (C) Joule-Thompson co-efficient (D) None of these

Description : (∂T/∂P)H is the mathematical expression for (A) Specific heat at constant pressure (Cp) (B) Specific heat at constant volume (Cv) (C) Joule-Thompson co-efficient (D) None of these

Last Answer : (C) Joule-Thompson co-efficient

The equation, Cp- Cv = R, is true for __________ gas. (A) No (B) Any real (C) Only ideal (D) Both (B) and (C)

Description : The equation, Cp- Cv = R, is true for __________ gas. (A) No (B) Any real (C) Only ideal (D) Both (B) and (C)

Last Answer : (C) Only ideal

Cp- Cv = R is valid for __________ gases. (A) Ideal (B) Very high pressure (C) Very low temperature (D) All of the above

Description : Cp- Cv = R is valid for __________ gases. (A) Ideal (B) Very high pressure (C) Very low temperature (D) All of the above

Last Answer : (A) Ideal

Work input to the air compressor with n as index of compression A. Increases with increase in value of n B. Decrease with increase in value of n C. remains same whatever the value of n D. first increase and then decreases with increase of value of n.

Description : Work input to the air compressor with n as index of compression A. Increases with increase in value of n B. Decrease with increase in value of n C. remains same whatever the value of n D. first increase and then decreases with increase of value of n.

Last Answer : ANSWER : A

For perfect gas a. cp – cv = R b. cp + cv = R c. cp / cv = R d. cp X cv = R Where cp & cv are specific heats at constant pressure and volume.

Description : For perfect gas a. cp – cv = R b. cp + cv = R c. cp / cv = R d. cp X cv = R Where cp & cv are specific heats at constant pressure and volume.

Last Answer : ANSWER a. CP – CV = R

Give relation between Cp and Cv.

Description : Give relation between Cp and Cv.

Last Answer : Ans. Cp – Cv = R

The gas constant is equal to  a. Cp – Cv  b. Cp + Cv  c. Cp – Cv + k  d. None of the above

Description : The gas constant is equal to  a. Cp – Cv  b. Cp + Cv  c. Cp – Cv + k  d. None of the above

Last Answer : Cp – Cv

The heat supplied to the gaS at constant volume is (where m = Mass of gas, cv = Specific heat at constant volume, cp = Specific heat at constant pressure, T2 – T1 = Rise in temperature, and R = Gas constant)  A. mR(T2 – T1)  B. mcv(T2 – T1)  C. mcp(T2 – T1)  D. mcp(T2 + T1)

Description : The heat supplied to the gaS at constant volume is (where m = Mass of gas, cv = Specific heat at constant volume, cp = Specific heat at constant pressure, T2 – T1 = Rise in temperature, and R = Gas constant)  A. mR(T2 – T1)  B. mcv(T2 – T1)  C. mcp(T2 – T1)  D. mcp(T2 + T1)

Last Answer : Answer: B

The ratio of specific heat at constant pressure (Cp) and specific heat at constant volume (cv) is  A. equal to one  B. less than one  C. greater than one  D. none of these

Description : The ratio of specific heat at constant pressure (Cp) and specific heat at constant volume (cv) is  A. equal to one  B. less than one  C. greater than one  D. none of these

Last Answer : Answer: C

Characteristic gas constant of a gas is equal to  (a) C/Cv  (b) Cv/Cp  (c) Cp – Cv  (d) Cp + Cv  (e) Cp x Cv

Description : Characteristic gas constant of a gas is equal to  (a) C/Cv  (b) Cv/Cp  (c) Cp – Cv  (d) Cp + Cv  (e) Cp x Cv

Last Answer : Answer : c

General gas equation is  (a) PV=nRT  (b) PV=mRT  (d) PV = C  (c) PV=KiRT  (e) Cp-Cv = Wj

Description : General gas equation is  (a) PV=nRT  (b) PV=mRT  (d) PV = C  (c) PV=KiRT  (e) Cp-Cv = Wj

Last Answer : Answer : b

Equal volumes of two monoatomic gases, A and B, at same temperature and pressure are mixed. The ratio of specific heats (Cp /Cv ) of the mixture will be (1) 1.67 (2) 0.83 (3) 1.50 (4) 3.3

Description : Equal volumes of two monoatomic gases, A and B, at same temperature and pressure are mixed. The ratio of specific heats (Cp /Cv ) of the mixture will be (1) 1.67 (2) 0.83 (3) 1.50 (4) 3.3

Last Answer : (1) 1.67

The two specific heats of gases are related by : (1) Cp + Cv = RJ (2) Cp –Cv = R/J (3) Cp – Cv = RJ (4) Cp /Cv = R

Description : The two specific heats of gases are related by : (1) Cp + Cv = RJ (2) Cp –Cv = R/J (3) Cp – Cv = RJ (4) Cp /Cv = R

Last Answer :  Cp –Cv = R/J

In the equation, PVn = constant, if the value of n = 1, then it represents a reversible __________ process. (A) Isothermal (B) Isobaric (C) Polytropic (D) Adiabatic

Description : In the equation, PVn = constant, if the value of n = 1, then it represents a reversible __________ process. (A) Isothermal (B) Isobaric (C) Polytropic (D) Adiabatic

Last Answer : (A) Isothermal

When the expansion of compression of gas takes place without transfer of heat to or from the gas the process is called  a. reversible  b. adiabatic  c. polytropic  d. isothermal

Description : When the expansion of compression of gas takes place without transfer of heat to or from the gas the process is called  a. reversible  b. adiabatic  c. polytropic  d. isothermal

Last Answer : adiabatic

A process, in which the temperature of the working substance remains constant during its expansion or compression, is called  A. isothermal process  B. hyperbolic process  C. adiabatic process  D. polytropic process

Description : A process, in which the temperature of the working substance remains constant during its expansion or compression, is called  A. isothermal process  B. hyperbolic process  C. adiabatic process  D. polytropic process

Last Answer : Answer: A

The expression for refractive index is given by a) N = v/c b) N = c/v c) N = cv d) N = 1/cv

Description : The expression for refractive index is given by a) N = v/c b) N = c/v c) N = cv d) N = 1/cv

Last Answer : b) N = c/v

If value of n is infinitely large in a polytropic process pV” = C, then the process is known as constant  (a) volume  (b) pressure  (c) temperature  (d) enthalpy  (e) entropy

Description : If value of n is infinitely large in a polytropic process pV” = C, then the process is known as constant  (a) volume  (b) pressure  (c) temperature  (d) enthalpy  (e) entropy

Last Answer : Answer : a

The value of n = 1 in the polytropic process indicates it to be  (a) reversible process  (b) isothermal process  (c) adiabatic process  (d) irreversible process  (e) free expansion process.

Description : The value of n = 1 in the polytropic process indicates it to be  (a) reversible process  (b) isothermal process  (c) adiabatic process  (d) irreversible process  (e) free expansion process.

Last Answer : Answer : b

The expression for the work done for a reversible polytropic process can be used to obtain the expression for work done for all processes, except reversible __________ process. (A) Isobaric (B) Isothermal (C) Adiabatic (D) None of these

Description : The expression for the work done for a reversible polytropic process can be used to obtain the expression for work done for all processes, except reversible __________ process. (A) Isobaric (B) Isothermal (C) Adiabatic (D) None of these

Last Answer : (B) Isothermal

The index of compression n tends to reach ratio of specific heats y when  (a) flow is uniform and steady  (b) process is isentropic  (c) process is isothermal  (d) process is isentropic and specific heat does not change with temperature  (e) process is isentropic and specific heat changes with temperature.

Description : The index of compression n tends to reach ratio of specific heats y when  (a) flow is uniform and steady  (b) process is isentropic  (c) process is isothermal  (d) process ... specific heat does not change with temperature  (e) process is isentropic and specific heat changes with temperature.

Last Answer : Answer : d

Which of the following diagramInternal energy is equal to the heat absorbed in case of a/an __________ process. (A) Constant volume (B) Polytropic (C) Adiabatic (D) Constant pressure s does not represent an Otto cycle?

Description : Which of the following diagrams does not represent an Otto cyInternal energy is equal to the heat absorbed in case of a/an __________ process. (A) Constant volume (B) Polytropic (C) Adiabatic (D) Constant pressure cle?

Last Answer : (A) Constant volume

In polytropic process (PV n = constant), if n = 1; it means a/an __________ process. (A) Adiabatic (B) Reversible (C) Isothermal (D) None of these

Description : In polytropic process (PV n = constant), if n = 1; it means a/an __________ process. (A) Adiabatic (B) Reversible (C) Isothermal (D) None of these

Last Answer : (C) Isothermal

For the chemical reaction P → Q, it is found that the rate of reaction doubles as the concentration of 'P' is doubled. If the reaction rate is proportional to Cp n , then what is the value of 'n' for this chemical reaction? (A) 0 (B) 1 (C) 2 (D) 3

Description : For the chemical reaction P → Q, it is found that the rate of reaction doubles as the concentration of 'P' is doubled. If the reaction rate is proportional to Cp n , then what is the value of 'n' for this chemical reaction? (A) 0 (B) 1 (C) 2 (D) 3

Last Answer : (B) 1

What is polytropic process ? Under what conditions it approaches isobaric, isothermal, and isometric process ? In which reversible process no work is done ?

Description : What is polytropic process ? Under what conditions it approaches isobaric, isothermal, and isometric process ? In which reversible process no work is done ?

Last Answer : A polytropic process is one that follows the equation pun = constant (index n may have values from – oc to + oo. This process approaches isobaric when n = 0, isothermal when n = 1, and isometric when n = . No work is done in isometric process.

Pick out the wrong statement. (A) Cp of monatomic gases such as metallic vapor is about 5 kcal/kg.atom (B) The heat capacity of solid inorganic substance is exactly equal to the heatcapacity of the substance in the molten state(C) There is an increase in entropy, when a spontaneous change occurs in anisolated system(D) At absolute zero temperature, the heat capacity for many pure crystallinesubstances is zero

Description : Pick out the wrong statement. (A) Cp of monatomic gases such as metallic vapor is about 5 kcal/kg.atom (B) The heat capacity of solid inorganic substance is exactly equal to the ... isolated system (D) At absolute zero temperature, the heat capacity for many pure crystalline substances is zero

Last Answer : (C) There is an increase in entropy, when a spontaneous change occurs in an isolated system

Determine number of coils in a helical compression spring, if modulus of rigidity is 80 Gpa and spring stiffness is 50 N/ mm. Assume wire diameter and spring index as 8 mm and 5 respectively a. 11.8 turns b. 12.8 turns c. 13.3 turns d. None of the above

Description : Determine number of coils in a helical compression spring, if modulus of rigidity is 80 Gpa and spring stiffness is 50 N/ mm. Assume wire diameter and spring index as 8 mm and 5 respectively a. 11.8 turns b. 12.8 turns c. 13.3 turns d. None of the above

Last Answer : b. 12.8 turns

Work done in an adiabatic process between a given pair of end states depends on  (a) the end states only  (b) particular adiabatic process  (c) the value of index n  (d) the value of heattransferred  (e) mass of the system.

Description : Work done in an adiabatic process between a given pair of end states depends on  (a) the end states only  (b) particular adiabatic process  (c) the value of index n  (d) the value of heattransferred  (e) mass of the system.

Last Answer : Answer : a

Calculate the recoverable waste heat (Q, in kCal/hour) from flue gases using the followingparameters: V (flow rate of the substance) 2000 m3/hr r (density of the flue gas): 0.9 kg/m3 Cp (specific heat of the substance): 0.20 kCal/kg oC DT (temperature difference): 120 oC h (recovery factor): 50% a. 21600 b. 43200 c. 25600 d. 34000

Description : Calculate the recoverable waste heat (Q, in kCal/hour) from flue gases using the followingparameters: V (flow rate of the substance) 2000 m3/hr r (density of the flue gas): 0.9 kg/m3 Cp (specific heat ... (temperature difference): 120 oC h (recovery factor): 50% a. 21600 b. 43200 c. 25600 d. 34000

Last Answer : 21600

Pick up the correct statement from the following: (A) Plain cement concrete is equally strong in compression as well as in tension (B) Slump test is performed to check concrete strength (C) Curing of concrete is done for proper compaction of cement (D) Fineness modulus is the index number expressing the relative sizes of both coarse and fine aggregates

Description : Pick up the correct statement from the following: (A) Plain cement concrete is equally strong in compression as well as in tension (B) Slump test is performed to check concrete strength (C ... D) Fineness modulus is the index number expressing the relative sizes of both coarse and fine aggregates

Last Answer : Option D

The expression for entropy change, ΔS = n Cp. ln (T2/T1), is valid for the __________ of a substance. (A) Simultaneous pressure & temperature change (B) Heating (C) Cooling (D) Both (B) and (C)

Description : The expression for entropy change, ΔS = n Cp. ln (T2/T1), is valid for the __________ of a substance. (A) Simultaneous pressure & temperature change (B) Heating (C) Cooling (D) Both (B) and (C)

Last Answer : (D) Both (B) and (C)

For a certain gas R = 320 J/kg.K and cv= 0.84kJ/kg.K. Find k?  a. 1.36  b. 1.37  c. 1.38  d. 1.39 formula: k= R / cv+1

Description : For a certain gas R = 320 J/kg.K and cv= 0.84kJ/kg.K. Find k?  a. 1.36  b. 1.37  c. 1.38  d. 1.39 formula: k= R / cv+1

Last Answer : 1.38