Gaseous State Test

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Gaseous State Test - 12

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Weekly Quiz Competition

Question 1
4 / -1

The value of van der Waals’ constant ‘a’ for the gases O₂, N₂, NH₃ and CH₄ are 1.360, 1.390, 4.170 and 2.253 L² atm mol^–2 respectively. The gas which can most easily be liquefied is:

A
O₂

B
N₂

C
NH₃

D
CH₄
Solution
The ease of liquification of a gas depends on their intermolecular force of attraction which in turn is measured in terms of van der Waals’ constant ‘a’.
Hence, the higher the value of ‘a’, the greater the intermolecular force of attraction, the easier the liquification.
In the present case, NH₃ has the highest ‘a’, can most easily be liquefied.
Question 2
4 / -1

The density of neon will be highest at:

A
STP

B
0°C, 2 atm

C
273°C, 1 atm

D
273°C, 2 atm
Solution
According to the ideal gas equation:
P = dRT/M i.e. d = PM/RT
As per the above equation at high pressure and low-temperature, density is maximum.
Question 3
4 / -1

The rate of diffusion of methane at a given temperature is twice that of a gas X. The molecular weight of X is:

A
64.0

B
32.0

C
4.0

D
8.0

Solution

The rate of diffusion of methane at a given temperature is twice that of gas X i.e. r_CH4= 2r_X
∵ The rate of diffusion is inversely proportional to the square root of its molar mass.
Therefore,

Thus, molecular mass of gas X is M_X= 64.0 g/mol
Question 4
4 / -1

According to kinetics theory of gases, for a diatomic molecule:

A
The pressure exerted by the gas is proportional to mean velocity of the molecule

B
The pressure exerted by the gas is proportional to the root mean velocity of the molecule

C
The root mean square velocity of the molecule is inversely proportional to the temperature.

D
The mean translational kinetic energy of the molecule is proportional to the absolute temperature.

Solution

As we know: KE = (3/2) RT
⇒ KE ∝ T
i.e. mean transitional kinetic energy of the molecules is proportional to the absolute temperature.
Question 5
4 / -1

At constant volume, for a fixed number of moles of a gas the pressure of the gas increases with rise of temperature due to:

A
Increase in average molecular speed

B
Increase rate of collisions amongst molecules

C
Increase in molecular attraction

D
Decrease in mean freed path
Question 6
4 / -1

Equal weights of ethane and hydrogen are mixed in an empty container at 25°C. The fraction of the total pressure exerted by hydrogen is:

A
1 : 2

B
1 : 1

C
1 : 16

D
15 : 16

Solution

Partial pressure of hydrogen/total pressure = mole fraction of hydrogen =15:16
Question 7
4 / -1

The ratio between the root mean square speed of H₂ at 50 K and that of O₂ at 800 K is:

A
4

B
2

C
1

D
¼

Solution

The rms velocity is directly proportional to the square root of temperature and inversely proportional to the square root of molecular weight.

The ratio between the root mean square velocity of H₂ at 50K and that of O₂ at 800K is
Question 8
4 / -1

The compressibility factor for an ideal gas is:

A
1.5

B
1.0

C
2.0

D
∞

Solution

The deviation of ideal behaviour is introduced by compressibility factor Z.
i.e. Z = PV/nRT
for ideal gas PV = nRT, therefore, Z is 1.
Question 9
4 / -1

The critical temperature of water is higher than that of O₂ because the H₂O molecule has:

A
Fewer electrons than O₂

B
Two covalent bonds

C
V-shape

D
Dipole moment.
Question 10
4 / -1

According to Graham’s law, at a given temperature the ratio of the rates of diffusionof gases A and B is given by (where, p and M are pressure and molecular weights of gases A and B respectively)

A

B

C

D

Solution

Hence C is correct.