At a fixed total pressure, humidity depends only on the (A) Partial pressure of vapour in the mixture (B) Heat capacity of the vapour (C) Density of the vapour (D) None of these

At a fixed total pressure, humidity depends only on the
(A) Partial pressure of vapour in the mixture
(B) Heat capacity of the vapour
(C) Density of the vapour
(D) None of these
by

1 Answer

Answer :

(A) Partial pressure of vapour in the mixture
by

Related questions

At a fixed pressure, the humidity depends upon the partial pressure of vapor in the mixture. Humidity of a vapour free gas is __________ percent. (A) 100 (B) 0 (C) 50 (D) Between 0 and 100

Description : At a fixed pressure, the humidity depends upon the partial pressure of vapor in the mixture. Humidity of a vapour free gas is __________ percent. (A) 100 (B) 0 (C) 50 (D) Between 0 and 100

Last Answer : (B) 0

When an unsaturated air-water mixture is heated at constant pressure, then (A) The partial pressure of water vapour increases (B) The specific humidity decreases (C) The relative humidity increases (D) The relative humidity decreases

Description : When an unsaturated air-water mixture is heated at constant pressure, then (A) The partial pressure of water vapour increases (B) The specific humidity decreases (C) The relative humidity increases (D) The relative humidity decreases

Last Answer : D) The relative humidity decreases

The ratio of partial pressure of water vapour in a mixture to the saturation pressure of water at the same temperature of the mixture is called as A. humidity B. partial humidity C. specific humidity D. relative humidity

Description : The ratio of partial pressure of water vapour in a mixture to the saturation pressure of water at the same temperature of the mixture is called as A. humidity B. partial humidity C. specific humidity D. relative humidity

Last Answer : ANSWER : D

When dry bulb temperature & wet bulb temperature of moist air is the same, it means that the (A) Partial pressure of water vapour is less than the total pressure (B) Humidity is < 100% & dew point temperature of air has not reached (C) Dew point temperature of air has not reached & air is not saturated fully (D) Air is fully saturated

Description : When dry bulb temperature & wet bulb temperature of moist air is the same, it means that the (A) Partial pressure of water vapour is less than the total pressure (B) Humidity is < 100% & dew ... Dew point temperature of air has not reached & air is not saturated fully (D) Air is fully saturated

Last Answer : (D) Air is fully saturated

An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively. The humidity of air sample expressed as kg of water vapour/kg of dry air is: (A) 0.048 (B) 0.079 (C) 0.122 (D) 0.152

Description : An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively ... air is: (A) 0.048 (B) 0.079 (C) 0.122 (D) 0.152

Last Answer : (D) 0.152

Which of the following remains constant during sensible cooling process? (A) Specific humidity (B) Partial pressure of vapour (C) Both (A) and (B)

Description : Which of the following remains constant during sensible cooling process? (A) Specific humidity (B) Partial pressure of vapour (C) Both (A) and (B)

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

Which of the following remains constant during evaporative cooling process with recirculated water supply? (A) Relative humidity (B) Partial pressure of vapour (C) Wet bulb temperature (D) None of these

Description : Which of the following remains constant during evaporative cooling process with recirculated water supply? (A) Relative humidity (B) Partial pressure of vapour (C) Wet bulb temperature (D) None of these

Last Answer : (C) Wet bulb temperature

Relative humidity is the ratio of the (A) Partial pressure of the vapour to the vapour pressure of the liquid at room temperature (B) Partial pressure of the vapour to the vapour pressure of the liquid at gas temperature (C) Actual humidity to saturation humidity (D) None of these

Description : Relative humidity is the ratio of the (A) Partial pressure of the vapour to the vapour pressure of the liquid at room temperature (B) Partial pressure of the vapour to the vapour pressure of the liquid at gas temperature (C) Actual humidity to saturation humidity (D) None of these

Last Answer : (B) Partial pressure of the vapour to the vapour pressure of the liquid at gas temperatur

Which of the following decreases during evaporative cooling process with recirculated water supply? (A) Wet bulb temperature (B) Relative humidity (C) Partial pressure of vapour (D) None of these

Description : Which of the following decreases during evaporative cooling process with recirculated water supply? (A) Wet bulb temperature (B) Relative humidity (C) Partial pressure of vapour (D) None of these

Last Answer : (D) None of these

Which of the following increases during evaporative cooling process with recirculated water supply? (A) Wet bulb temperature (B) Relative humidity (C) Partial pressure of vapour (D) Both (B) and (C)

Description : Which of the following increases during evaporative cooling process with recirculated water supply? (A) Wet bulb temperature (B) Relative humidity (C) Partial pressure of vapour (D) Both (B) and (C)

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

Dew point of an air-water vapor mixture (A) Decreases with decrease in pressure (B) At constant humidity & total pressure is fixed (C) Corresponding to any point on the humidity chart is obtained by projecting a line through this point parallel to the temperature axis and to the saturation curve (D) All 'a', 'b' & 'c'

Description : Dew point of an air-water vapor mixture (A) Decreases with decrease in pressure (B) At constant humidity & total pressure is fixed (C) Corresponding to any point on the humidity chart is obtained by projecting a ... to the temperature axis and to the saturation curve (D) All 'a', 'b' & 'c'

Last Answer : (D) All 'a', 'b' & 'c'

Condensation of a vapour-gas mixture just begins, when (where, p = partial pressure of the vapour P = vapour pressure of the liquid). (A) p = P (B) p >>P (C) p < P (D) p << P

Description : Condensation of a vapour-gas mixture just begins, when (where, p = partial pressure of the vapour P = vapour pressure of the liquid). (A) p = P (B) p >>P (C) p < P (D) p

Last Answer : (A) p = P

What is the specific humidity? A. the ratio of the mass of water vapour to the mass of the total mixture of air and water vapour B. the ratio of the mass of dry air to the mass of the total mixture of air and water vapour C. the ratio of the mass of dry air to the mass of water vapour in a mixture of air and water vapour D. the ratio of the mass of water vapour to the mass of dry air in a mixture of air and water vapour

Description : What is the specific humidity? A. the ratio of the mass of water vapour to the mass of the total mixture of air and water vapour B. the ratio of the mass of dry air to the mass of the total mixture ... ratio of the mass of water vapour to the mass of dry air in a mixture of air and water vapour

Last Answer : ANSWER : D

The temperature at which water boils depends mainly on ------? A. Air temperature B. Relative humidity C. Air pressure (Answer) D. Air density E. The specific heat of air

Description : The temperature at which water boils depends mainly on ------? A. Air temperature B. Relative humidity C. Air pressure (Answer) D. Air density E. The specific heat of air

Last Answer : C. Air pressure (Answer)

The temperature to which a vapour gas mixture must be cooled (at varying humidity) to become saturated is called the __________ temperature. (A) Dew point (B) Wet bulb (C) Dry bulb (D) None of these

Description : The temperature to which a vapour gas mixture must be cooled (at varying humidity) to become saturated is called the __________ temperature. (A) Dew point (B) Wet bulb (C) Dry bulb (D) None of these

Last Answer : (D) None of these

When the liquid phase and vapour phase of a binary system obeys Raoult's and Dalton's law respectively, the relative volatility is the ratio of (A) Vapour pressure of component A to that of component B (B) Vapour pressure of component A to the total pressure (C) Vapour pressure of component A to the partial pressure of A (D) Partial pressure of component A to the total pressure

Description : When the liquid phase and vapour phase of a binary system obeys Raoult's and Dalton's law respectively, the relative volatility is the ratio of (A) Vapour pressure of component A to that of ... to the partial pressure of A (D) Partial pressure of component A to the total pressure

Last Answer : (A) Vapour pressure of component A to that of component B

Henry's law states that the (A) Partial pressure of a component over a solution is proportional to its mole fraction in the liquid (B) Partial pressure of a component over a solution is proportional to the mole fraction in the vapour (C) Vapour pressure is equal to the product of the mole fraction and total pressure (D) Partial pressure is equal to the product of the mole fraction and total pressure

Description : Henry's law states that the (A) Partial pressure of a component over a solution is proportional to its mole fraction in the liquid (B) Partial pressure of a component over a solution ... pressure (D) Partial pressure is equal to the product of the mole fraction and total pressure

Last Answer : (A) Partial pressure of a component over a solution is proportional to its mole fraction in the liquid

An indication of sensible heat content in air-water vapour mixture is a) wet bulb temperature b) dew point temperature c) density of air d) dry bulb temperature

Description : An indication of sensible heat content in air-water vapour mixture is a) wet bulb temperature b) dew point temperature c) density of air d) dry bulb temperature

Last Answer : d) dry bulb temperature

Pick out the wrong statement (A) A horizontal line on the humidity chart indicates the temperature changes at constant molal humidity (B) When water is cooled from 80 to 70°C by exposure to the air with a wet bulb temperature of 60°C, then both the approach & the range would be 10°C (C) For unsaturated air-water vapor mixture at atmospheric conditions, the wet bulb temperature & adiabatic cooling lines are the same (D) Relative saturation of unsaturated mixture of water vapor & air cannot be increased by either reducing the mixture temperature or by increasing the total pressure

Description : Pick out the wrong statement (A) A horizontal line on the humidity chart indicates the temperature changes at constant molal humidity (B) When water is cooled from 80 to 70°C by exposure ... & air cannot be increased by either reducing the mixture temperature or by increasing the total pressure

Last Answer : (D) Relative saturation of unsaturated mixture of water vapor & air cannot be increased by either reducing the mixture temperature or by increasing the total pressure

Pick out the correct statement. (A) Higher hold up of the solid in the rotary dryer results in better exposure of the solids to the gas (B) The 'Hatta number' is important in problems involving gas absorption without chemical reaction (C) For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion (D) Total reflux in case of distillation operation requires infinite number of plates for a binary system separation

Description : Pick out the correct statement. (A) Higher hold up of the solid in the rotary dryer results in better exposure of the solids to the gas (B) The 'Hatta number' is ... reflux in case of distillation operation requires infinite number of plates for a binary system separation

Last Answer : (C) For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion

The partial pressure of each constituent present in an alloy is __________ the total vapor pressure exerted by the alloy. (A) Less than (B) Equal to (C) More than (D) Either (B) or (C); depends on the type of alloy

Description : The partial pressure of each constituent present in an alloy is __________ the total vapor pressure exerted by the alloy. (A) Less than (B) Equal to (C) More than (D) Either (B) or (C); depends on the type of alloy

Last Answer : (A) Less than

The relative saturation of a partially saturated mixture of vapour and gas can be increased by __________ of the mixture. (A) Reducing the total pressure (B) Increasing the total pressure (C) Reducing the temperature (D) Both (B) and (C)

Description : The relative saturation of a partially saturated mixture of vapour and gas can be increased by __________ of the mixture. (A) Reducing the total pressure (B) Increasing the total pressure (C) Reducing the temperature (D) Both (B) and (C)

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

During dehumidification of unsaturated air wet bulb temperature & partial pressure of vapor are not constant. However, during evaporative cooling process with recirculated water supply, the __________ remains constant. (A) Wet bulb temperature (B) Partial pressure of water vapor (C) Relative humidity (D) None of these

Description : During dehumidification of unsaturated air wet bulb temperature & partial pressure of vapor are not constant. However, during evaporative cooling process with recirculated water supply, the __________ remains ... pressure of water vapor (C) Relative humidity (D) None of these

Last Answer : (A) Wet bulb temperature

Which of the following can be calculated theoretically using steam table and Dalton's law of partial pressure; if the relative humidity and dry bulb temperature of moist air is known? (A) Dew point (B) Humidity ratio (C) Wet bulb temperature (D) None of these

Description : Which of the following can be calculated theoretically using steam table and Dalton's law of partial pressure; if the relative humidity and dry bulb temperature of moist air is known? (A) Dew point (B) Humidity ratio (C) Wet bulb temperature (D) None of these

Last Answer : (C) Wet bulb temperature

gas which is collected over water becomes moistened due to water vapor, exerts its own partial pressure at the gas temperature, which is termed as its (A) Aqueous tension (B) Saturated humidity (C) Vapor pressure

Description : gas which is collected over water becomes moistened due to water vapor, exerts its own partial pressure at the gas temperature, which is termed as its (A) Aqueous tension (B) Saturated humidity (C) Vapor pressure

Last Answer : Option A

In saturated gas, the (A) Vapour is in equilibrium with the liquid at the gas temperature (B) Vapour is in equilibrium with the liquid at the room temperature (C) Partial pressure of vapour equals the vapour pressure of the liquid at room temperature (D) None of these

Description : In saturated gas, the (A) Vapour is in equilibrium with the liquid at the gas temperature (B) Vapour is in equilibrium with the liquid at the room temperature (C) Partial pressure of vapour equals the vapour pressure of the liquid at room temperature (D) None of these

Last Answer : (A) Vapour is in equilibrium with the liquid at the gas temperature

Moisture content of a substance when at equilibrium with a given partial pressure of the vapour is called the __________ moisture. (A) Free (B) Unbound (C) Equilibrium (D) Bound

Description : Moisture content of a substance when at equilibrium with a given partial pressure of the vapour is called the __________ moisture. (A) Free (B) Unbound (C) Equilibrium (D) Bound

Last Answer : (C) Equilibrium

Which of the following parameters remains constant during chemical dehumidification? (A) Dry bulb temperature (B) Partial pressure of vapour (C) Wet bulb temperature (D) None of these

Description : Which of the following parameters remains constant during chemical dehumidification? (A) Dry bulb temperature (B) Partial pressure of vapour (C) Wet bulb temperature (D) None of these

Last Answer : (A) Dry bulb temperature

According to Avogadro’s Hypothesis  (a) the molecular weights of all the perfect gases occupy the same volume under same conditions of pressure and temperature  (b) the sum of partial pressure of mixture of two gases is sum of the two  (c) product of the gas constant and the molecular weight of an ideal gas is constant  (d) gases have two values of specific heat  (e) all systems can be regarded as closed systems.

Description : According to Avogadro's Hypothesis  (a) the molecular weights of all the perfect gases occupy the same volume under same conditions of pressure and temperature  (b) the sum of partial pressure of ... gases have two values of specific heat  (e) all systems can be regarded as closed systems.

Last Answer : Answer : a

If a mixture of two gases has a total pressure of 5.7 ATM. If one gas has a partial pressure of 4.1 ATM what is the partial pressure of the other gas?

Description : If a mixture of two gases has a total pressure of 5.7 ATM. If one gas has a partial pressure of 4.1 ATM what is the partial pressure of the other gas?

Last Answer : 1.6 ATM

A 0.064 kg of octane vapor (MW = 114) is mixed with0.91 kg of air (MW = 29.0) in the manifold of an Engine. The total pressure in the manifold is 86.1 kPa, and a temperature is 290 K. assume octane behaves ideally. What is the partial pressure of the air in the mixture in KPa?  a. 46.8  b. 48.6  c. 84.6  d. 64.8

Description : A 0.064 kg of octane vapor (MW = 114) is mixed with0.91 kg of air (MW = 29.0) in the manifold of an Engine. The total pressure in the manifold is 86.1 kPa, and a temperature is 290 K. assume octane behaves ideally. What is ... of the air in the mixture in KPa?  a. 46.8  b. 48.6  c. 84.6  d. 64.8

Last Answer : 84.6

According to Dalton’s law, the total pres sure of the mixture of gases is equal to  (a) greater of the partial pressures of all  (b) average of the partial pressures of all  (c) sum of the partial pressures of all  (d) sum of the partial pressures of all divided by average molecular weight  (e) atmospheric pressure.

Description : According to Dalton's law, the total pres sure of the mixture of gases is equal to  (a) greater of the partial pressures of all  (b) average of the partial pressures of all  (c) sum ... all  (d) sum of the partial pressures of all divided by average molecular weight  (e) atmospheric pressure.

Last Answer : Answer : c

The capacity of a pneumatic conveying system depends upon the (A) Bulk density of materials (B) Pressure of the conveying air (C) Diameter of the conveying line (D) All (A), (B) and (C)

Description : The capacity of a pneumatic conveying system depends upon the (A) Bulk density of materials (B) Pressure of the conveying air (C) Diameter of the conveying line (D) All (A), (B) and (C)

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

Relative humidity is a) the ratio of water vapour in the air compared to the total amount water vapour the air could contain at a given temperature b) equal to the dry bulb temperature divided by the wet bulb temperature c) equal to the wet bulb temperature divided by the dry bulb temperature d) the ratio of the mass of water vapour divided by the mass of dry air e) the ratio of the mass of water vapour divided by the mass of wet air

Description : Relative humidity is a) the ratio of water vapour in the air compared to the total amount water vapour the air could contain at a given temperature b) equal to the dry bulb temperature divided by the wet bulb ... of dry air e) the ratio of the mass of water vapour divided by the mass of wet air

Last Answer : ANSWER : A

The partial molar enthalpy of a component in an ideal binary gas mixture of composition Z, at a temperature T and pressure P, is a function only of (A) T (B) T and P (C) T, P and Z (D) T and Z

Description : The partial molar enthalpy of a component in an ideal binary gas mixture of composition Z, at a temperature T and pressure P, is a function only of (A) T (B) T and P (C) T, P and Z (D) T and Z

Last Answer : (B) T and P

Inside an aeroplane flying at a high altitude, (a) the pressure is the same as that outside (b) normal atmospheric pressure is maintained by the use of air pumps (c) the pressure inside is less than the pressure outside (d) normal humidity and partial vacuum are maintained

Description : Inside an aeroplane flying at a high altitude, (a) the pressure is the same as that outside (b) normal atmospheric pressure is maintained by the use of air pumps (c) the pressure inside is less than the pressure outside (d) normal humidity and partial vacuum are maintained

Last Answer : Ans:(b)

On a day when the partial pressure of water vapor remains constant, what happens as the temperature rises?  a. the relative humidity increases  b. the relative humidity decreases  c. the relative humidity remains constant  d. the air would eventually become saturated

Description : On a day when the partial pressure of water vapor remains constant, what happens as the temperature rises?  a. the relative humidity increases  b. the relative humidity decreases  c. the relative humidity remains constant  d. the air would eventually become saturated

Last Answer : the relative humidity decreases

_________is the partial pressure of water vapor at the existing temperature divided by the equilibrium vapor pressure of water at the existing temperature.  a. vacuum pressure  b. relative humidity  c. absolute pressure  d. vapor pressure

Description : _________is the partial pressure of water vapor at the existing temperature divided by the equilibrium vapor pressure of water at the existing temperature.  a. vacuum pressure  b. relative humidity  c. absolute pressure  d. vapor pressure

Last Answer : relative humidity

Relative humidity is the ratio of actual vapour pressure to the saturation vapour pressure (A) At the same temperature (B) At the same pressure (C) In the same volume (D) In the atmosphere

Description : Relative humidity is the ratio of actual vapour pressure to the saturation vapour pressure (A) At the same temperature (B) At the same pressure (C) In the same volume (D) In the atmosphere

Last Answer : Answer: Option A

Pick up the correct statement from the following: (A) Absolute humidity at a given temperature is equal to weight of moisture present in a unit volume (B) Relative humidity is the ratio of actual vapour pressure and saturation vapour pressure at the same temperature (C) Relative humidity is the ratio of the weight of the vapours present per unit volume to the weight of vapours which could be contained at the same temperature when fully saturated (D) All the above

Description : Pick up the correct statement from the following: (A) Absolute humidity at a given temperature is equal to weight of moisture present in a unit volume (B) Relative humidity is the ratio of ... of vapours which could be contained at the same temperature when fully saturated (D) All the above

Last Answer : Answer: Option D

The lysimeter helps in the estimation of (1) Evapotranspiration (2) Relative humidity (3) Vapour pressure (4) Wind direction

Description : The lysimeter helps in the estimation of (1) Evapotranspiration (2) Relative humidity (3) Vapour pressure (4) Wind direction

Last Answer : Evapotranspiration

Vapour lock is a. complete or partial stoppage of fuel supply due to vaporization of the fuel b. locking of carburetor due to high vapor pressure c. excess fuel supply to the engine d. supply of liquid fuel to the engine

Description : Vapour lock is a. complete or partial stoppage of fuel supply due to vaporization of the fuel b. locking of carburetor due to high vapor pressure c. excess fuel supply to the engine d. supply of liquid fuel to the engine

Last Answer : ANSWER a. complete or partial stoppage of fuel supply due to vaporization of the fuel

For a solution of volatile liquids, the partial vapour pressure of each component in solution is directly proportional to its (a) Molarity (b) Mole fraction (c) Molality (d) Normality

Description : For a solution of volatile liquids, the partial vapour pressure of each component in solution is directly proportional to its (a) Molarity (b) Mole fraction (c) Molality (d) Normality

Last Answer : Ans:(b)

Pressure exerted by fully saturated air, is known (A) Partial pressure (B) Saturation pressure (C) Saturation vapour pressure (D) Both (c) and (d) of the above

Description : Pressure exerted by fully saturated air, is known (A) Partial pressure (B) Saturation pressure (C) Saturation vapour pressure (D) Both (c) and (d) of the above

Last Answer : Answer: Option D

In a barometer, mercury is preferred over water because (a) mercury is a good conductor of heat (b) mercury is shining and therefore its level can be read easily (c) mercury is available in pure form (d) mercury has high density and low vapour pressure

Description : In a barometer, mercury is preferred over water because (a) mercury is a good conductor of heat (b) mercury is shining and therefore its level can be read easily (c) mercury is available in pure form (d) mercury has high density and low vapour pressure

Last Answer : Ans:(d)

With increase in absolute humidity, the dew point of an unsaturated mixture of air and water vapor (at constant pressure and temperature). (A) Increases (B) Remains unchanged (C) Decreases (D) Decreases linearly

Description : With increase in absolute humidity, the dew point of an unsaturated mixture of air and water vapor (at constant pressure and temperature). (A) Increases (B) Remains unchanged (C) Decreases (D) Decreases linearly

Last Answer : (A) Increases

Pick out the wrong statement. (A) The mole fraction of solute is directly proportional to the molality of a 'dilute' solution (B) For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is nonlinear in the case of steady state unimolal unidirectional diffusion (C) Azeotropes obey Raoult's law at all temperature (D) The relative volatility of a binary mixture at the Azeotropic composition is 1

Description : Pick out the wrong statement. (A) The mole fraction of solute is directly proportional to the molality of a 'dilute' solution (B) For a non-reacting binary mixture of ideal gases, the partial ... at all temperature (D) The relative volatility of a binary mixture at the Azeotropic composition is 1

Last Answer : (C) Azeotropes obey Raoult's law at all temperature

Fugacity of a component in an ideal gas mixture is equal to the partial pressure of that component in the mixture. The fugacity of each component in a stable homogeneous solution at constant pressure and temperature __________ as its mole fraction increases. (A) Decreases (B) Decreases exponentially (C) Increases (D) Remain constant

Description : Fugacity of a component in an ideal gas mixture is equal to the partial pressure of that component in the mixture. The fugacity of each component in a stable homogeneous solution at constant pressure and ... increases. (A) Decreases (B) Decreases exponentially (C) Increases (D) Remain constant

Last Answer : (C) Increases

In an ideal gas mixture, fugacity of a species is equal to its (A) Vapor pressure (B) Partial pressure (C) Chemical potential (D) None of these

Description : In an ideal gas mixture, fugacity of a species is equal to its (A) Vapor pressure (B) Partial pressure (C) Chemical potential (D) None of these

Last Answer : (B) Partial pressure

Pick out the wrong statement. (A) Activity co-efficient is dimensionless. (B) In case of an ideal gas, the fugacity is equal to its pressure. (C) In a mixture of ideal gases, the fugacity of a component is equal to the partial pressure of the component. (D) The fugacity co-efficient is zero for an ideal gas

Description : Pick out the wrong statement. (A) Activity co-efficient is dimensionless. (B) In case of an ideal gas, the fugacity is equal to its pressure. (C) In a mixture of ideal gases, the fugacity of ... equal to the partial pressure of the component. (D) The fugacity co-efficient is zero for an ideal gas

Last Answer : (D) The fugacity co-efficient is zero for an ideal gas