A gas diffuses four time quickly as oxygen. The molecular weight of gas is:

  • 2

  • 4

  • 8

  • 16

Which among the following mixtures of gases at room temperature does not obey Dalton's law of partial pressure-

  • He and O2

  • NH3 and HCl

  • H2 and He

  • N2 and He

Themolecular radius for a certain gas = 1.25 A. What is a reasonable estimate of the magnitude of the van der Wails constant, b, for the gas?

  • 0.98 × 10–2 litre/mole

  • 1.43 × 10–2 litre/mole

  • 1.97 × 10–2 litre/mole

  • 3.33 × 10–2 litre/mole

At lower temperature, all gases except H2 and He show:

  • Negative deviation

  • Positive deviation

  • Positive and negative deviation

  • None of the above

2 gms of hydrogen diffuses from a container in 10 minutes. How many gms of oxygen would diffuse through the same time under similar conditions?

  • 0.5 gm                         

  • 4 gm

  • 6 gm                             

  • 8 gm

The mean free path (λ) of a gas sample is given by:

  •  λ=2πσ2N                               

  •  λ=1/2πσ2N

  •  λ=2πμσ2N                               

  • none of these

Which is lighter than dry air?

  • Moist air                             

  • SO2

  • Cl2                                      

  • O2

The ratio a/b (the terms used in van der Waals' equation) has the unit-

  • atm litre mol-1                           

  • atm dm3 mol-1

  • dyne cm mol-1                           

  • All of the above

At relatively high pressure, van der Waals' equation reduces to-

  • PV = RT

  • PV = RT + a/v

  • PV = RT + Pb

  • PV = RT - a/V2

The maximum deviation from ideal gas behaviour takes place -  

  • At high temperature and low pressure

  • At low temperature and high pressure

  • At high temperature and high pressure

  • At low temperature and low pressure

Joule-Thomson coefficient (∂T/∂P)H for an ideal gas is:

  • zero                                 

  • +ve

  • -ve                                   

  • none of these

All the three states H2O, i.e., the triple point for H2O the equilibrium,

                       Ice ⇌Water⇌Vapour exist at:

  • 3.85 mm and 0.0981 °C

  • 4.58 mm and 0.0098 °C

  • 760 mm and 0°C

  • none of the above

The unit of van der Waals' constant 'a' is:

  • atm litre2 mol-2                       

  • dyne cm4 mol-2

  • newton m4 mol-2                     

  • All of the above           

The unit of van der Waals' constant 'b' is :

  • cm3 mol-1

  • litre mol-1

  • m3 mol-1

  • all of these 

The beans are cooked in pressure cooker, because -                                   

  • Boiling point increases with increasing pressure

  • Boiling point decreases with increasing pressure

  • Extra pressure of pressure cooker softens the beans

  • Internal energy is not lost while cooking in pressure cooker

An ideal gas cannot be liquified because                                          

  • its critical temperature is always above 0°C

  • its molecules are relatively smaller in size

  • it solidifies before becoming a liquid

  • forces operating between its molecules are negligible

 The compressibility factor for H2 and He is usually:

  • >1                                     

  • =1

  • <1                                     

  • either of these

Boyle's law is applicable in :

  • Isobaric process

  • Isochoric process

  • Isothermal process

  • Adiabatic process

The temperature of the gas is raised from 27°C to 927°C the root mean square velocity is        

  •  92727 times of the earlier value

  • same as before

  • halved

  • doubled

500 mL of nitrogen at 27°C are cooled to -5°C at the same pressure. The new volume becomes-      

  • 326.32 mL                     

  • 446.66 mL

  • 546.32 mL                     

  • 771.56 mL

A gas cannot be liquefied if:

  • Forces of attraction are low under ordinary conditions

  • Forces of attraction are high under ordinary conditions

  • Forces of attraction are zero under ordinary conditions

  • Forces of attraction are either high or low under ordinary conditions

In the case of hydrogen and helium the van der Waals' forces are-

  • Strong                 

  • Very strong

  • Weak                   

  • None of the above

With the increase of pressure, the mean free path:

  • decreases                             

  • increases

  • becomes zero                       

  • remains the same

The compressibility factor of an ideal gas is:

  • zero                         

  • infinite

  • 1                               

  • -1

The correct value of the gas constant 'R' is close to 

  • 0.082 L atm K

  • 0.082 L atm K-1 mol-1

  • 0.082 L atm-1 K mol-1

  • 0.082 L-1 atm-1 K mol

The partial pressure of a dry gas is:

  • less than that of wet gas

  • greater than that of wet gas

  • equal to that of wet gas

  • none of the above

The number of molecules present in 1 mL of gas or vapor at STP is:

  • called Loschmidt's number

  • equal to 2.617 x 1019 per mL

  • both (1) and (2)

  • none of the above

 Air at sea level is dense. This is a practical application of:

  • Boyle's law                         

  • Charles' law

  • Avogadro's law                   

  • Dalton's law

In van der Waals' equation of state of the gas, the constant 'b' is a measure of:

  • Intermolecular collisions per unit volume

  • Intermolecular attraction

  • Volume occupied by molecules

  • Intermolecular repulsions

For 1 mole of gas, the average kinetic energy is given as E. The urms of gas is :

  • [2E/M]1/2

  • [3E/M]1/2

  • [2E/3M]1/2

  • [3E/2M]1/2

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