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Worksheets

Real gases

Total questions: 22

Worksheet time: 15mins

Name
Class
Date
1.

If Z is the compressibility factor, van der Waals’ equation at low pressure can be written as :

a)

Z=1-Pb/RT

b)

Z=1+Pb/RT

c)

Z = 1+RT/Pb

d)

Z = 1-a/VmRT

2.

Which intermolecular force is most responsible in allowing xenon gas to liquefy?

a)

Instantaneous dipole induced dipole

b)

Ion dipole

c)

Ionic

d)

Dipole-dipole

3.

The temperature at which oxygen molecules have the same root mean square

speed as helium atoms have at 300 K is :

(Atomic masses : He = 4 u, O = 16 u)

a)

1200 K

b)

600 K

c)

300 K

d)

2400 K

4.

The compressibility factor for a real gas at high pressure is :

a)

1-Pb/RT

b)

1+ RT/Pb

c)

1

d)

1+Pb/RT

5.

The relationship among most probable velocity, average velocity and root mean

Square velocity is respectively :

a)

√2 : √(8/π) : √3

b)

√2 :√3 : √(8/π )

c)

√3 : √(8/π) : √2

d)

√(8/π) : √3 : √2

6.

Value of gas constant R is

a)

0.082 L atm

b)

0.987 cal mol-1 K-1

c)

8.3 J mol-1 K-1

d)

83 erg mol-1K-1

7.

By how many folds the temperature of a gas would increase when the root mean

Square velocity of the gas molecules in a container of fixed volume is increased from 5×104 cm/s to 10×104 cm/s?

a)

four

b)

three

c)

two

d)

six

8.

Kinetic theory of gases proves

a)

Only boyle’s law

b)

Only Charle’s law

c)

Only Avogadro’s law

d)

all of these

9.

Which one of the following is the wrong assumption of kinetic theory of gases?

a)

All the molecules move in a straight line between collision and with the same velocity.

b)

Molecules are separated by great distances compared to their sizes.

c)

Pressure is the result of elastic collision of molecules with the container’s wall.

d)

Momentum and energy always remain conserved.

10.

‘a’ and ‘b’ are Vander Waal’s constants for gases. Chlorine is more easily liquified than ethane because:

a)

a for Cl2 < a for C2H6 but b for Cl2 > b for C2H6

b)

a for Cl2 > a for C2H6 but b for Cl2 < b for C2H6

c)

a and b for Cl2 > a and b for C2H6

d)

a and b for Cl2 < a and b for C2H6

11.

A gaseous compound of nitrogen and hydrogen contains 12.5% (by mass) of

Hydrogen. The density of the compound relative to hydrogen is 16. The molecular formula of the compound is :

a)

NH2

b)

NH3

c)

N3H

d)

N2H4

12.

The one that is extensively used as a piezo electric material is

a)

quartz

b)

amorphous silica

c)

trydymite

d)

mica

13.

Which primitive unit cell has unequal edge lengths and all axial lengths different from 900.

a)

Monoclinic

b)

Triclinic

c)

Tetragonal

d)

Hexagonal

14.

In Van der waals equation of state of the gas law, the constant b is a measure of

a)

Intermolecular repulsions

b)

Intermolecular attraction

c)

Volume occupied by molecules

d)

Intermolecular collisions per unit volume.

15.

A pressure cooker reduces cooking time for food because

a)

Heat is more evenly distributed in the cooking space.

b)

B.P of water involved in cooking is increased

c)

The higher pressure inside the cooker crushes the food.

d)

Cooking involves chemical changes helped by a rise in temperature.

16.

According to kinetic theory of gases, in an ideal gas, between two successive collisions a gas molecule travels

a)

In a circular path

b)

In wavy path

c)

In a straight line path

d)

with an accelerated velocity

17.

Which of the following is the correct correction for intermolecular forces in Van der Waals equation?

a)

(V-nb)

b)

(P + n2a / V2)

c)

RT

d)

(RT)-1

18.

The van der Waals equation is a modification of ideal gas equation. Which of the following factor is not accounted for the modification?

a)

Volume of gas particles.

b)

Attractive forces between particles.

c)

Position of the particles.

19.

In van der Waals equation, pressure correction is due to force of attraction between molecules.

a)

True

b)

False

20.

The value of constant 'a' in van der Waals equation for various gases are given below:


Nitrogen gas, N2= 1.390 L2 atm mol-2

Oxygen gas, O2 = 1.360 L2 atm mol-2

Ammonia gas, NH3 = 4.170 L2 atm mol-2

Methane gas, CH4 = 2.253 L2 atm mol-2

Arrange these gases in the order of decreasing strength of intermolecular forces.

a)

NH3 < CH4 < N2 < O2

b)

NH3 > CH4 > N2 > O2

c)

O2 < N2 < CH4 < NH3

d)

O2 > N2 > CH4 > NH3

21.

The value of constant 'a' in van der Waals equation for various gases are given below:


Nitrogen gas, N2= 1.390 L2 atm mol-2

Oxygen gas, O2 = 1.360 L2 atm mol-2

Ammonia gas, NH3 = 4.170 L2 atm mol-2

Methane gas, CH4 = 2.253 L2 atm mol-2


Arrange these gases in the order of most ideal to least ideal gas.

a)

NH3 < CH4 < N2 < O2

b)

NH3 > CH4 > N2 > O2

c)

O2 < N2 < CH4 < NH3

d)

O2 > N2 > CH4 > NH3

22.

From the van der Waals constant 'b' for H2, CO2 and N2 gas, which of the gas have the largest volume?


Hydrogen gas, H2 = 0.02661 L mol-1

Carbon dioxide, CO2 = 0.04267 L mol-1

Nitrogen gas, N2 = 0.03913 L mol-1

a)

Hydrogen gas. H2

b)

Carbon dioxide, CO2

c)

Nitrogen gas, N2