UNIT#03 GASES Flashcards
At constant temperature when the pressure of a gas is increased three times then its volume becomes:
V/3
(P ∝ 1/V)
Under what conditions the density of an ideal gas will be maximum at:
➡Low temperature
➡High Pressure
(d= PV/RT)
If 1/V is plotted on x-axis and pressure on Y-axis at constant temperature, what should appear:
Straight line passing thorugh origin
The general gas equation to know the volumes of the gas at various temperatures is:
Vt = V° (1+t/273)
A mono-atomic substance can store energy only in the form of:
Translational Motion
A graph between pressure and product of pressure and volume at constant temperature and number of moles is:
Straight line parallel to x-axis
If both temperature and volme of a gas are doubled, the pressure
Remain unchanged
WHich one is the form of general gas equation:
➡PV=nRT
➡PV=RT
➡P1V1/T1 = P2V2/T2
Volume of a gas at S.T.P is 10dm3 at what temperature its volume will become 30dm3, keeping pressure constant
819K
(V1T1 = V2T2)
Which of the follwoing pairs of gases possess equal volume at S.T.P
0.5 mole of NO and 16g of O2
(Equal volume of all ideal gas at same temperature and pressure contain equal number of molecules and moles)
Which is incorrect about ideal gas
➡No force of attraction between molecules❌
➡No example in nature❌
➡Can be liquified easily✅
➡Obey gas laws at all conditions of temperature and pressure❌
A gas initially at 27 °C is heated up to 327 °C, its average kinetic energy will be:
Double
The coorect value for geenral gas constant is:
8.314 x 10^7 erg mol-1 K-1
In gases and liquids, temperature is the measure of _____ kinetic energies of molecules.
Average translational
The molar volume of nitrogen gas is maximum at:
130 °C and 1 atm
8g of methane and 2g of hydrogen are mixed and kept at 760 mm pressure at 273K, the total volume occupied by the mixture will be:
33.6 dm3
What is NOT true about gases:
➡They are highly compressible❌
➡They have only vibrational motion✅
➡Sudden expansion of gases cause cooling❌
➡They exert pressure on the walls of the vessel❌
For a definite mass of ideal gas at constant temperature, the plot of which pair of species will give a curved graph.
P vs V
A pressure of 0.101325 bar when expressed in atmosphere represents:
0.1 atm
(1 atm = 1.10325 bar)
Dimensons of the pressure are the same as that of:
Force per unit volume
Gases deviate from ideal behaviour at high pressure. Which of the following is correct for non-ideality?
At high pressure, the volume of the gas becomes insignificant
Under high pressure which of the following gas show more ideality in character:
N2
Ideality of gas will be more:
➡Less Intermolcular Force
➡Smaller Size
➡Non-Polar
➡Smaller mass
When 200cm3 of a gas at constant pressure is heated, its volume:
Increases
(V ∝ T)
The product of PV of a gas has unit of:
Work
(Joule)
Under what condition if temperature and pressure will a real gas behave most like an ideal gas?
➡High Temperature
➡Low Pressure
Absolute temperature of a gas is direclty proportional to average ___.
Translational Kinetic Energy
An ideal gas cant be liquefied because:
Forces between its molecuels are negligible
The compressibility factor ‘Z’ for an ideal gas is:
Equal to one
In dm3 atm K-1 mol-1, 2.0 g of hydrogen gas is heated from 27 °C to 327 °C. Which of the following is incorrect
The number of moles of the gas increases
(closed container)
A pressure of a gas is due to:
Molecular impacts against the walls of vessel
The compressiiblity actor, Z i.e the extent to which a real gas deviated from ideal behaviour is given by:
Z= PV/RT
Which of the following gases has the lowest r.m.s velocity at 25 °C
Cl2
Value of a ideal gas constant R does not depend upon:
Units of Temperature
“a” is called co-efficient of attraction in Van der Waal’s equation for real gases the unit of “a” is:
Nm+4/mol2
What will be the new volume if temperature and pressure both are reduced to half
Remains same
Very small values of Van der Waal’s constant in his equation for a particular gas shows that:
Least attractive forces are present among the molecules of the gas
Excluded volume is ____ times the actual volume of gas molecules
Four
(b=4Vm)
The constant ‘a’ in Van Der Waal’s equation is maximum for:
(a=attraction per unit volume)
Ammonia
(Ammonia has hydrogen bonding, Strong intermolecular force)
The average kinetic energy of the gas molecules is:
Directly proprotional to its absolute temperature
All the collisions between the particles o gases are elastic in nature. What is meant by “elastic collision”
No change in the kinetic energy
Which one of the following expression represent the Avogadro law?
V=RnT/P
(When T and P are constant)
The root mean square velocity of gases is inversely proportional to square root of their:
Molar mass
c (r.m.s) = √3RT/M
The number of molecules in 22.4 dm3 of H2 gas at 0 °C and 1 atm are:
6.02 x 10^23
There are four gases H2, N2, He, and CO2 at 0°C. Which gas shown greater non-ideal.
CO2
(Mass ∝ Intermolecular Force ∝ Non-Ideal Behaviour)
Identify the value of R at STP:
0.0821 atm dm3 K-1 mole-1
In the Van Der Waals equation, “b” represents that:
Excluded volume per mole
Gas is enclosed in a container of 20cm3 with the moving piston. According to kinetic theory o gases, what is the effect on freely moving molecules of the gas if temperature is increased from 20°C to 100°C?
Volume will be increased
(At constant pressure, by increasing temperature volume of a gas molecules)
Which of the following is the correct equation to calculate relative molecular mass of a gas:
M = mRT/PV
Which of the statmeent is applicable for both ideal and real gases molecules?
➡Have no forces of attraction❌
➡Collisions between the molecules is elastic❌
➡Molecules are in random motion✅
➡The actual volume of gas is negligible as compared to the volume of the gas❌
At absolute zero the molecules of hydrogen gas will have:
All the motion are ceased
According to the general gas euation, density of an ideal gas depends upon:
➡Pressure
➡Temperature
➡Molar mass of the gas
➡All of the above✅
The actual volume of gas molecules is considered neglegibile at following pressures.
2 atm
The unit is ___ commonly used by meterologist
Millibar
Plasma is difficult to maintain at:
Low Temperature
Effusion is the movement of a gas through extremely small opening of molecular size into region of ____ pressure.
Low
PV/nRT for an ideal gas is called
Compressibility Factor
The sum of moel fraction of the gases in a mixture of gases is:
Always 1
According to Avogadro’s law, .889 g of 1dm3 H2 and 1.4384g of 1 dm3 O2 have number of molecules
Same
Calculate the mass of 1dm3 of NH3 gas at 3°C and 1mm Hg pressure, considering that NH3 is ideally behaving
0.99 g
212-degree Farhenheit is expressed Kelvin as:
373
For non-ideal gas:
PV/NRT is not equal to Z
R does not depend upon:
Pressure
Which law is applicable while respiration:
Dalton’s Law
Which has the highest rate of diffusion:
NH3SO2
Effusions are:
Inversely to the square root of mass
KMT is discovered by:
Bernoulli
Which of these gases cannot liquify:
➡H2
➡He
The general gas equation is also known as:
Ideal
When temperature increases, the isotherm moves:
Away from both axis
Volume in an ideal gas is directly related to;
➡n
➡T
➡P
According to kinetic molecular theory absolute temperature is directly proportional to ___ of molecules.
Average translational kinetic Energy
Calculate the density of methane in g/L at -450°C and 300 torr pressure.
0.338
The general gas equation is also known as;
Ideal gas equation
The general gas equation is used for;
Ideal gas
General Gas Equation
PV=nRT
Liquids have no definite shape it is because
The molecules of liquid are in constant motion by sliding over each other
A class of materials with highly variable mechanical and optical properties that solidify from the molten state without crystallization are called
Amorphous solids
Gases deviate from Ideal behaviour at high pressure. Which of the following is correct for non idealty
At high pressure, the intermolecular attractions become significant
Under high pressure which of the following gas show more ideality in character
N2
CO2
NH3
SO2
N2
Absolute zero is
-459.67°F
The correct value of general gas constant is
8.314×10⁷ erg/mol.K
An ideal gas can’t be liquefied because
Forces between its molecules are negligible
A fire extinguisher delivers 2.2 kg of CO2. volume of CO2 at STP is
1120 dm3
When 200 ml of a gas at constant pressure is hated its volume
Increases
The product of PV of a gas is a unit of
Work
Gases exert pressure on the walls of the container because the gas molecules
Collide with walls of container
Which one of the following is absolute zero
Zero kelvin
The number of molecules in 0.0112m3 of Methane at 0°C and pressure of 760 mm Hg is
3.01×10^23
Which of the following will have same number of molecules at STP
280 cm3 of CO2 and 280 cm3 of N2O
The graph between pressure and inverse of volume at constant pressure and number of moles
Straight line passing through the origin
In a closed vessel of 1000 cm3, H2 gas is heated from 27°C to 127°C. Which statement is not correct
The number of moles of gas increases
The molecules of gas show more deviation from Ideal behaviour at low temperature because
Attractive force dominate at low temperature
The gas was our best applicable under the condition
Low pressure and high temperature
The root mean square velocity is expressed as
(3RT/M)½
At constant pressure volume of given mass of gas is directly proportional to
Absolute Temperature
Absolute zero is unattainable temperature, current attempts have resulted in the lowest temperature of
10–⁵ K
If temperature is increasing continuously then constant k in PV=k will
Increase
What will happen to density of an ideal gas if both temperature and pressure are doubled
Remain same
100m³ of a gas at 3atm and 27°C is transferred into a container having volume 300 m³ and temperature 327°C. Pressure in new container will be
2 atm
Value of general gas constant R depends on
Units of P and V
Which of the molecules have maximum root mean square velocity at 25°C
NH3
Which of the following gas show maximum ideal behaviour
N2
The density of Methane at 2atm pressure at 27°C is
1.3 gdm-3
The correct mathematical form of Avogadro’s law is
V1\V2=n1\n2
The deviation of gas from Ideal behaviour is maximum at
-10°C and 5atm
If Absolute Temperature is doubled and the pressure is increased to four times, the volume of gas is
Half
The average kinetic energy of gas molecules is
Directly proportional to its Absolute Temperature
The compressibility factor Z for an ideal gas is
Equal to 1
If we increase or decrease the amount of heat to a liquid, its boiling point will
Remain constant
Which is the correct order of boiling points
H2O >HF >NH3 >CH4
Evaporation of water depends upon
Surface area and intermolecular forces
speed of air above the liquid surface
humidity in air
110°C boiling point of water corresponds to the external pressure
Between 760 to1200 torr
Boiling point of compound is mostly raised by
Intermolecular hydrogen bonding
Which has greater enthalpy of vaporization
I2 (iodine)
Identify incorrect statement about evaporation
Exothermic
Which mathematical relationship doesn’t correctly represent behaviour of an ideal gas
Pressure is inversely proportional to density
Maximum vapour pressure is shown by
50 cm3 ethanol and 1dm3 ethanol
Evaporation occurs at
All temperatures
Which one is the most accurate method for the measurement of vapour pressure
Manometric method
The vapour pressure of methanol at 40°C is less than
Ether
The volume of a given mass of gas is _____ to the inverse of the pressure
Direclty Proprotional
At constant temperature, by doubling the pressure volume of gas reduced to _____.
1/2 of original volume
Gases aresoluble in water at:
➡Low Temperature
➡High Pressure
The SI Unit of pressure is Nm-3. 10^03 atm is equal to:
0.101325 KPa
Which one has more mass at STP
1 dm^3 of O2
Two gases having same temperature and pressure will have:
➡Same volume
➡Same no. of molecules
➡Same moles
For a given mass with initial volume “V”, if pressure is reduced t one half and absolute temperature is increasesd two times. The volume will become;
4V
Which of the following expressions at constant pressure represents Charles’s law
V` ∝ T
Which of the following relation is true for the density of an ideal gas
PM/RT
If absolute temperature and pressure of gas is doubled then volume o gas will:
Remain unchanged
The expression for root mean square velocity is:
c(r.m.s) = √3/2RT/M
16g of each of CH4 and He are in a container at 50°C. The ratio of kinetic energy is:
1:4
According to kinetic molceular theory the kinetic energy of gas molecules varies directly with:
Absolute Temperature
Which of the following is NOT the basic assumption of the kinetic theory of gases:
➡The collisions among the molecule of the gas are perfectly elastic❌
➡The molecules of the gas are always in the state of ceaseless haphhazard motion❌
➡The pressure of a gas is due to collision of gas molecules with the walls of container❌
➡The molecules exert appreciable attraction on each other✅
In gases, Temperature is the measure of;
Average translational Kinetic Energy
Observed pressure of gas on the walls of container is less than actual pressure due to:
Inter molecular attractive forces
A gas that has highest value for Van der Waals coefficient of attraction
NH3
A gas under what conditions will behave non-ideally:
➡Temperature: Low
➡Pressure; High
(At low temperature and high pressure intermolecular forces develop significantly)
Gases deviate from ideal behaviour at high pressure. Which of the following is correct for non-ideality?
At high pressure, the intermolecular attraction become significant
Which of the following shows strange behaviour when subjected to gradual increase in pressure at 0°C
CO2
In Boyles law, plot between pressure and constant ‘K’ obtained is::
Straight Line parallel to pressure axis
If volume of O2 is 11.2dm3 at STP, then the number of moles would be:
0.5 moles
Pressure remaining constant at which temperature the volume of gas will become twice of what it is at 0°C
546K
If temperature of 1 mole of gas is raised by 1K, then it would absorb ____ amount of energy.
0.0821 dm3 atm
When the value of general gas constant ‘R’ us given as 8.314. The relevant units will be;
J. mol-1. K-1
In the ideal gas equation PV = nRT, the value of R depends upon:
Units of measurement
The gas having highest density is:
Cl2
According to Kinetic theory of gases which relation is correct:
PV = 2/3 kT
The molecular velocity of a gas is:
Proportional to root mean square velocity of a gas
The root mean square velocity is equivalent to:
➡C (r.m.s) = √3RT/M
➡C (r.m.s) = √3PV/M
➡C (r.m.s) = √3P/d
If the temperature of a gas is increased four times then its average K.E.
Increases 4 times
All of the following equations are expression for the ideal gas law:
➡PV = nRT
➡PV/T = constant
➡P1V1/T1 = P2V2/T2
Real gases show more deviation from ideal behaviour under which of the following conditions:
➡at low temperature
➡high pressure
In Van der Waal’s equation, if the value of ‘a’ and ‘b’ are zero for a certain gas, then the gas is:
Ideal
Real gases deviate at low temperature from ideal behaviour due to;
Significant increase in the intermolecular attractive forces
Effective volume of molecules per mole of a gas is ____ times greater than actual volume of 1 mole of gas molecules
4
The compressibility factor, (Z=PV/nRT) has value at which a gas show maximum non-ideality in behaviour:
1.5
(Greater the value of ‘Z’, greater the real behaviour)
Gases exert pressure on the walls of the container because the gas molecules:
Collide with the walls of the container
Which one of the following is absolute zero
0 K
Crystalline solids are classified on the basis of bonding into ___ types.
Four
The number of molecules in 0.0112 m^3 of methane at 0°C and pressure of 760 mm Hg is:
3.01 x 10^23
Which of the following will gave the same number of molecules at STP
280 cm^3 of CO2 and 280 cm^3 of N2O
The graph between pressure and inverse of volume at constant temperature and number of moles
A straight line passing through the origin
In a closed vessel of 1000 cm^3, H2 gas is heated from 27°C to 127°C. Which statement is correct?
The number of moles of gas increases
The molecules of gas show more deviation from ideal behaviour at low temperatures, because;
Attractive force dominates at low temperature
The gas laws are best applicable under the conditions:
➡Low P
➡High T
The root means square velocity is expressed as:
(3RT/M)^1/2
At constant pressure, the volume of a given mass of a gas is directly proportional to;
Absolute temperature
Absolute zero is an unattainable temperature, current attempts have resulted in the lowest of:
10^-5 K
If the temperature is increasing continuously then constant ‘k’ in PV=k will;
Increase
What will happen to the density of an ideal gas, if both temperature and pressure are doubled;
Remain same
100 m^3 of gas at 3atm and 27°C is transferred into a container having a volume of 300 m^3 and a temperature of 327°C. Pressure in the new container will be;
2 atm
The value of the general gas constant ‘R’ depends upon;
Units of P and V
Which of the following molecules has a maximum root mean square velocity at 25°C?
NH3
Which of the following gas show maximum ideal behaviour
N2
Which mathematical relationship doesn’t correctly represent the behaviour of an ideal gas
P ∝ 1/d
The density of methane at 2 atm pressure at 27°C is;
1.3 g/dm^3
The correct mathematical form of Avogadro’s law is:
V1/V2 = n1/n2
Which one is most real at STP:
NH3
The deviation of gas from ideal behaviour is maximum at:
-10°C and 5.0 atm
(At low temperatures or high pressures, real gases deviate significantly from ideal gas behaviour)
If the absolute temperature is doubled and the pressure is increased to 4 times, the volume of gas is;
Half
The average K.E of the gas molecules is;
Directly proportional to its absolute temperature
The compressibility factor (Z) for an ideal gas is;
Equal to one
At constant pressure, the volume of a given mass of a gas is directly proportional to;
Temperature
The volume of a gas at S.T.P is 10 dm^3 at which temperature its volume will become 30 dm^3, keeping the pressure constant
819 K
Absolute zero is an unattainable temperature, current attempts have resulted in the lowest temperature of;
10^-5 K
Which of the following pairs of gases possess equal volume at STP
➡0.5 moles of NO
➡16 g O2
Which of the following pairs have the same rates of diffusion;
➡N2O
➡CO2
Units of PV are the same as that of;
Energy
If the temperature is increasing continuously then constant ‘K’ in PV=K will;
Increase
What will happen to the density of an ideal gas, if both temperature and pressure are doubled;
Remain same
Absolute zero is;
-459.4°F
A gas initially at 27°C is heated up to 327°C, and its average K.E will be;
Doubled
100m^3 of a gas at 3 atm and 27°C is transferred into a container having a volume of 300m^3 with a temperature of 327°C. Pressure in new container will ber:
2 atm
Value of general gas constant ‘R” depends upon:
Units of P and V
The correct value of general gas constant R is;
8.314 x 10^7 erg mol^-1 K-1
The absolute temperature of a gas is directly proportional to the average;
Translational kinetic energy
Which pair of gases do not obey Dalton’s law of partial pressure;
➡NH3
➡HCl
The ratio of the rate of diffusion of equal volumes of He and SO2 is:
4:1
NH3 gas diffuses twice faster than the gas;
C5H8
At the same temperature and pressure, two balloons are separately filled with H2 and O2. If O2 escapes at the rate of 60 cm/hr, the rate of diffusion of hydrogen will be:
240 cm/hr
Which of the following molecules has a maximum root mean square velocity at 25°C
NH3
Two balloons are filled with equal moles of H2 and He at STP. Which balloon will contract first if the same size holes are made in both of them?
Ballon filled with H2
An ideal gas can’t be liquified because;
Forces between its molecules are negligible
Which of the following gas show maximum ideal behaviour
N2
The SI unit of ‘a’ is:
Nm^4mol^-2
The least values of Van der Waal’s constants ‘a’ and ‘b’ are for:
Hydrogen
Which mathematical relationship doesn’t correctly represent the behaviour of an ideal gas?
➡P ∝ CT❌
➡P ∝ dT❌
➡P ∝ 1/d✅
Which statement is correct regarding Van Der Waal’s equation:
a NH3 > a N2 > and b NH3 > b N2
A fire extinguisher delivers 2.2 kg of CO2. The volume of CO2 at STP is;
1120 dm^3
The ratio of partial pressure of helium to the hydrogen in a mixture of 4g o hydrogen and 4g of helium is:
1/2
A mixture of 64g each of SO2, O3, O2 and CH4 is taken in a cylinder, the correct order of their partial pressure is:
CH4>O2>O3>SO2
(Partial Pressure ∝ No. of moles ∝ m/M)
The number of molecules in 0.0112 m^3 of methane at 0°C and pressure 760mmHg is:
3.01 x 10^23
Which of the following will have the same number of molecules at STP
➡280 cm^3 of CO2
➡280 cm^3 of N2O
The partial pressure of oxygen in the lungs is;
116 torr
Gases deviate from ideal behaviour at high pressure. Which of the following is correct for non-ideality:
At high pressure, the inter-molecular attractions become insignificant
Evaporation is designated as a cooling process because of the reason:
High energy molecules leave behind the low energy molecules and cause cooling
Evaporating water depends upon the following;
➡Surface area and intermolecular forces
➡Speed of the air above the liquid surface
➡Humidity of air
The graph between and inverse of volume at constant temperature and number of moles;
A straight line passing through the origin
If both the temperature and volume of a gas are doubled, the pressure
Remain unchanged
In a closed vessel of 1000 cm^3, H2 gas is heated from 27°C to 127°C. Which statement is not correct?
➡The rate of collision increases❌
➡Pressure of gas increases❌
➡The energy of gas molecules increases❌
➡The number of moles of gas ✅
Which one is the form of a general gas equation:
➡PV=nRT
➡PV=RT
➡P1V1/T1 = P2V2/T2
The sudden expansion of the gas from high pressure towards the low-pressure causes:
Decrease in temperature
The molecules of gas show more deviation from ideal behaviour at low temperatures, because
Attractive forces dominate at low temperature
Which of the following temperature scale can not have a negative value:
Kelvin
The gas laws are best applicable under the conditions;
➡Low P
➡High T
Under high pressure which of the following gas show more ideality in character
N2
Which is incorrect about ideal gas?
➡No force of attraction between molecules❌
➡No example in nature❌
➡Can be liquefied easily❌
➡Obey gas laws under all conditions of temperature and pressure✅
Gases exert pressure on the walls of containers because the gas molecules:
Collide with the walls of the container
