Chemistry Multiple Choice Questions & Answers (MCQs) on “States of Matter – Liquefaction of Gases”.
1. Which of The following is a critical temperature for Carbon dioxide?
a) 32-degree centigrade
b) 30.98-degree centigrade
c) 40-degree centigrade
d) 30.91 degree Kelvin
Answer: b
Clarification: The critical temperature of carbon dioxide is a maximum temperature where the carbon dioxide can remain as a liquid below this temperature. The carbon dioxide is gas so the critical temperature for Carbon dioxide is 30.98 degrees centigrade.
2. Which of the following is Greater?
a) Boyle’s temperature
b) Boyle’s temperature = critical temperature
c) Critical temperature
d) Boyle’s temperature = 1/critical temperature
Answer: a
Clarification: Boyle’s temperature TB is given by a/Rb critical temperature TC is given by 8a/27Rb, where a is the pressure correction term and b is a volume correction term as per van der Waal’s equation. So Boyle’s temperature is greater than the critical temperature.
3. What is the ratio of critical temperature to Boyle’s temperature of the same gas?
a) 8/27
b) 27/8
c) 8
d) 27
Answer: a
Clarification: The maximum temperature gas can remain liquid is known as critical temperature. The temperature till which a gas behaves like an ideal gas is Boyle’s temperature. Boyle’s temperature TB is given by a/Rb critical temperature Tc is given by 8a/27Rb. So the ratio is 8/27.
4. A fluid is a _______________
a) gas
b) liquid
c) solid
d) both gas and liquid
Answer: d
Clarification: A fluid is a gas or liquid that can be used to recognize the continuity. The fluid is something deforms under shear stress application and flows from one place to another, it is also a subset of States of matter.
5. A gas that is liquefied by applying pressure below critical temperature is called ____________ of the substance.
a) vapor
b) liquid
c) solid
d) plasma
Answer: a
Clarification: At critical temperature liquid state changes into gaseous state continuously the surface that separates both this state disappears and gas below critical temperature can be liquefied by applying pressure and this is called vapor of the substance.
6. If the value of a is greater, what does it mean?
a) the gas liquefies easily
b) the gas cannot liquify easily
c) gas obeys ideal gas law
d) gas particles have random motion
Answer: a
Clarification: The value of an in van der Waals equation is a measure of the magnitude of intermolecular attractive forces within a gas. It is independent of temperature and pressure. As attractive forces are more, the gas can be liquefied easily.
7. Which of the following can be the value of “b” for Helium?
a) 23.71 x 10-6 m2/mol
b) 23.71 x 10-6 m3/mol
c) 23.71 x 10-6 m3 mol
d) 23.71 x 10-6 m/mol
Answer: b
Clarification: From van der Waal’s equation (P – an2/V2)(V – nb) = nRT, we have that units of volume and number of moles x b are same. So L = mol x b; units of b is L/mol otherwise can be written as m3/mol.
8. The value of b for carbon dioxide is given as 42.69 x 10-6m3/mol. What do you think is the volume of a molecule?
a) 7.59 m3
b) 7.03 m3
c) 76.09 m3
d) 7.09 m3
Answer:d
Clarification: From van der Waal’s equation (P – an2/V2)(V – nb) = nRT, we know that V = b/NA = 42.69 x 10-6m3/mol/6.023 x 1023 molecules/mol. That equals 7.09 m3/molecule. So the volume of a molecule is 7.09m3.
9. In van der Waal’s equation, b is known as ______________
a) volume constant
b) pressure constant
c) volume correction
d) pressure correction
Answer: c
Clarification: In the van der Waal’s equation (P – an2/V2)(V – nb) = nRT, b is the volume correction term and is 4 times as the volume of a molecule. The letter a is the pressure correction term in the van der Waal’s equation.
10. Which of the following is an expression for Boyle’s temperature?
a) a/Rb
b) 27a/R
c) a/b
d) Ra/8b
Answer: a
Clarification: Boyle’s temperature Tb is given a/Rb, where a and b are the van der Waal’s constants for pressure and volume correction. The temperature till which a gas behaves like an ideal gas is Boyle’s temperature.