intro
MCQs 1:
Which gas cannot be liquefied using Linde's method?
Topic: Gas Liquefaction Methods
Correct Answer: C) Hydrogen (H2)
- Linde's method is used for the liquefaction of gases.
- However, not all gases can be liquefied using this method.
- Hydrogen (H2) is one such gas that cannot be liquefied using Linde's method due to its extremely low critical temperature (-238˚C).
- Therefore, the correct answer is C, "Hydrogen (H2)". Other gases like H2 and Helium (He) can be liquefied using Claud's method.
MCQs 2:
What happens to the kinetic energy of a gas in a closed vessel when it is heated from 300K to 600K?
Topic: Kinetic Molecular Theory (KMT) of Gases
Correct Answer: A) Doubles
- The Kinetic Molecular Theory of gases states that the average kinetic energy of gas molecules is directly proportional to the absolute temperature of the gas.
- In this scenario, when the temperature is doubled from 300K to 600K, according to the theory, the kinetic energy of the gas should also double.
- Therefore, the correct answer is A), "Doubles".
MCQs 3:
Charles’s law is only satisfied if temperature is taken on which scale?
Topic: Gas Laws - Charles's Law
Correct Answer: A) Kelvin (K)
- Charles's Law, a fundamental principle in the study of gases, postulates that the volume of an ideal gas is directly proportional to its absolute temperature, assuming at constant pressure.
- This law is specifically based on the Kelvin scale, which is an absolute temperature scale.
- Thus, the correct answer is A), "Kelvin (K)".
MCQs 4:
What is the Vander Waal's equation for real gases?
Topic: Real Gases - Vander Waals Equation
Correct Answer: A) Answer 1
- The Vander Waals equation is a mathematical model that describes the behavior of real gases.
- This equation accounts for the actual sizes of gas particles and the attractive forces between them, which are not considered in the ideal gas law.
- Therefore, the correct answer is A), "Answer 1".
MCQs 5:
The general gas equation is a combination of which laws?
Topic: Gas Laws - General Gas Equation
Correct Answer: D) All of the above
- The general gas equation (PV = nRT) combines multiple gas laws, including Boyle's Law, Avogadro's Law, and Charles's Law.
- Boyle's Law describes the inverse relationship between the pressure and volume of a gas at constant temperature, while Avogadro's Law states that equal volumes of all gases contain equal numbers of particles at the same temperature and pressure.
- Charles's Law, on the other hand, proposes that the volume of a gas is directly proportional to its absolute temperature at constant pressure.
- Therefore, the correct answer is D), "All of the above".
MCQs 6:
Considering the Vander Waal's constant 'a' for gases O2, N2, NH3, and CH4 are 1.360, 1.390, 4.179, and 2.253 l^2 atm moles^-2 respectively, which gas can be most easily liquefied?
Topic: Gas Liquefaction - Vander Waals Constant
Correct Answer: C) Ammonia (NH3)
- The Vander Waals constant 'a' is an indirect measure of the intermolecular attractive forces in a gas.
- A higher 'a' value indicates stronger intermolecular forces, making the gas easier to liquefy.
- Among the given gases, ammonia (NH3) has the highest 'a' value (4.179), indicating the strongest intermolecular forces. This is due to the presence of hydrogen bonding in ammonia, which is absent in the other gases.
- Therefore, the correct answer is C), "Ammonia (NH3)".
MCQs 7:
At what temperature do the Celsius and Fahrenheit scales give the same reading?
Topic: Temperature Scales - Celsius and Fahrenheit
Correct Answer: C) -40°C
- The Celsius and Fahrenheit scales are two different systems used to measure temperature.
- While they typically provide different readings for a given temperature, there is one point at which they intersect.
- This intersection occurs at -40 degrees, where both scales provide the same reading.
- Therefore, the correct answer is C), "-40°C".
Question 8:
Which law states that equal volumes of all ideal gases at the same temperature and pressure contain an equal number of molecules?
Topic: Gas Laws - Avogadro's Law
Correct Answer: B) Avogadro's Law
- Avogadro's law states that equal volumes of all ideal gases, at the same temperature and pressure, contain the same number of molecules.
- Boyle's law, Charles's law, and Dalton's law describe different aspects of gas behavior.
- Therefore, the correct answer is B), "Avogadro's Law".
Question 9:
What happens to the density of water when it freezes?
Topic: States of Matter - Density Change
Correct Answer: A) Decreases
- The freezing of water into ice leads to an increase in volume, which results in a decrease in density.
- This is because ice occupies about 9% more space than the same volume of water.
- Therefore, the correct answer is A), "Decreases".
Question 10:
CO2 and SO2 are both triatomic molecules, but the heat of vaporization of SO2 is greater than CO2. What is the reason for this?
Topic: Intermolecular Forces - Heat of Vaporization
Correct Answer: C) SO2 is polar and CO2 is non-polar
- The heat of vaporization of a substance is influenced by the strength of the intermolecular forces present.
- SO2 is a polar molecule, which means it has stronger intermolecular forces than CO2, a non-polar molecule.
- The greater electronegativity of sulfur, the size of SO2 molecules, or the acidity of SO2 does not directly contribute to the higher heat of vaporization.
- Therefore, the correct answer is C), "SO2 is polar and CO2 is non-polar".
Question 11:
The van der Waals equation is used to describe the behavior of which type of gases?
Topic: Gas Laws - van der Waals Equation
Correct Answer: A) Real gases
- The van der Waals equation is a modification of the ideal gas law that considers the finite size of molecules and intermolecular attractions.
- It is typically applied to real gases, which do not conform perfectly to the ideal gas law.
- The equation does not specifically describe mixtures of gases, ideal gases, or diatomic gases.
- Therefore, the correct answer is A), "Real gases".
Question 12:
Which of the following gases has the lowest root mean square velocity at 25°C?
Topic: Gas Properties - Root Mean Square Velocity
Correct Answer: D) Cl2
- The root mean square velocity of a gas is determined by its temperature and molar mass.
- At a given temperature, gases with higher molar masses will have lower root mean square velocities.
- Among the given options, Chlorine gas (Cl2) has the highest molar mass (71 g/mol), resulting in the lowest root mean square velocity.
- Therefore, the correct answer is D), "Cl2".
Question 13:
What happens to the volume of a gas when the pressure is doubled at a constant temperature?
Topic: Gas Laws - Pressure and Volume Relationship
Correct Answer: C) Decreases by half
- Boyle's law explains the inverse relationship between pressure and volume of a gas at a constant temperature.
- If the pressure is doubled, the volume of the gas would decrease to half in order to maintain the constant product of pressure and volume.
- The options of volume increasing, remaining the same, or decreasing by a quarter do not adhere to Boyle's law.
- Therefore, the correct answer is C), "Decreases by half".
Question 14:
What is the effect on a gas's behavior when the pressure is decreased?
Topic: Gas Laws - Effect of Pressure
Correct Answer: A) The gas becomes closer to an ideal gas
- The equations describing ideal gases assume no intermolecular forces and perfect compliance to the gas laws at all pressures.
- Real gases, however, deviate from ideal behavior at high pressures due to the presence of intermolecular forces and finite molecular size.
- By reducing pressure, a gas can exhibit behavior more closely aligned with the ideal gas laws.
- Therefore, the correct answer is A), "The gas becomes closer to an ideal gas".
MCQs 15:
Which postulate of the Kinetic Molecular Theory (KMT) explains Charles's Law?
Topic: Gas Laws - Kinetic Molecular Theory
Correct Answer: B) The kinetic energy of the gas molecules increases with the increase in temperature
- Charles's Law states that the volume of a given mass of gas is directly proportional to its absolute temperature, provided the pressure remains constant.
- According to KMT, the average kinetic energy of gas molecules is directly proportional to the absolute temperature of the gas.
- Thus, the postulate that kinetic energy increases with temperature supports Charles's Law.
- Therefore, the correct answer is B), "The kinetic energy of the gas molecules increases with the increase in temperature".
MCQs 16:
At which condition would the density of neon be the highest?
Topic: Gas Properties - Density
Correct Answer: B) 0∘ C, 2 atm
- The density of a gas is greatly influenced by its temperature and pressure.
- Higher pressure and lower temperature generally result in a higher density because the gas particles are closer together.
- Among the given conditions, 0∘ C, 2 atm provides both a low temperature and a high pressure.
- Therefore, the correct answer is B), "0∘ C, 2 atm".
MCQs 17:
What happens when a gas sample is compressed at a constant temperature from 15 atm to 60 atm, and its volume changes from 76.0cm3 to 20cm3?
Topic: Behavior of Gases - Compression
Correct Answer: B) The gas displays non-ideal behavior
- Boyle's law states that, at a constant temperature, the volume of a given mass of gas is inversely proportional to its pressure.
- If the gas were ideal, increasing the pressure 4 times would decrease the volume to ¼ of its original size according to Boyle's law.
- However, in this scenario, the decrease in volume doesn't comply with Boyle's law, indicating non-ideal behavior.
- Therefore, the correct answer is B), "The gas displays non-ideal behavior".
MCQs 18:
Which of the following gases has the most non-ideal behavior?
Topic: Behavior of Gases - Non-Ideal Behavior
Correct Answer: B) CO2
- Non-ideal behavior in gases can be attributed to increased molar mass, size, and stronger intermolecular forces leading to greater polarizability.
- CO2, with its larger molar mass compared to the other gases listed, exhibits greater deviation from ideal behavior.
- Therefore, the correct answer is B), "CO2".
MCQs 19:
Under which conditions will a real gas most closely mimic the behavior of an ideal gas?
Topic: Gas Laws - Conditions for Ideal Behavior
Correct Answer: D) High Temperature, Low Pressure
- Ideal behavior in gases is typically seen under conditions of low pressure and high temperature.
- High temperature allows the gas molecules to overcome intermolecular forces, while low pressure reduces the interaction between molecules.
- Therefore, the correct answer is D), "High Temperature, Low Pressure".
MCQs 20:
What is the compressibility factor for an ideal gas?
Topic: Gas Properties - Compressibility Factor
Correct Answer: C) Unity
- The compressibility factor, commonly denoted as Z, is a useful metric in gas physics.
- It is calculated using the formula Z=PV/nRT, where P is the pressure, V is the volume, n is the number of moles, R is the universal gas constant, and T is the temperature.
- For an ideal gas, the compressibility factor is always unity.
- Therefore, the correct answer is C), "Unity".
MCQs 21:
Which postulate of the kinetic molecular theory (KMT) of gases do real gases deviate from?
Topic: Behavior of Gases - Deviation from KMT
Correct Answer: D) Gas molecules have no intermolecular attractive forces
- The kinetic molecular theory (KMT) of gases provides an approximate description of the behavior of gases.
- However, real gases often deviate from these theoretical predictions.
- A notable deviation is observed in the postulate that gas molecules have no forces of attraction. Real gases do exhibit forces of attraction between molecules.
- Therefore, the correct answer is D), "Gas molecules have no intermolecular attractive forces".
Question 22:
What is the compressibility factor for ideal gases?
Topic: Gas Laws - Compressibility Factor
Correct Answer: B) 1
- The compressibility factor provides a measure of how much a real gas deviates from the ideal gas behavior.
- It is given by the formula Z=PV/nRT, where P, V, n, R, and T represent pressure, volume, number of moles, the universal gas constant, and temperature, respectively.
- In the case of ideal gases, this factor is 1.
- Therefore, the correct answer is B), "1".
Question 23:
What is the mathematical representation of Avogadro’s law?
Topic: Gas Laws - Avogadro’s Law
Correct Answer: C) V = kn
- Avogadro's law states that equal volumes of all gases, at the same temperature and pressure, have the same number of molecules.
- Mathematically, it is expressed as V = kn, where V is the volume of the gas, k is a constant, and n is the number of moles.
- Therefore, the correct answer is C), "V = kn".
Question 24:
What is the value of absolute zero?
Topic: Thermodynamics - Absolute Zero
Correct Answer: C) -273°C
- Absolute zero is the lowest temperature theoretically possible, at which the motion of particles that constitutes heat would be minimal. It's a cornerstone concept of thermodynamics.
- It is equal to -273.15 degrees Celsius or -459.67 degrees Fahrenheit.
- Therefore, the correct answer is C), "-273°C".
Question 25:
The General gas equation combines which laws?
Topic: Gas Laws - General Gas Equation
Correct Answer: D) All of these
- The general gas equation, also referred to as the ideal gas law, combines Boyle's Law, Charles' Law, and Avogadro's Law.
- It is represented as PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the universal gas constant, and T is the temperature.
- Therefore, the correct answer is D), "All of these".
Question 26:
Can an ideal gas that follows the kinetic theory of gases be liquefied if:
Topic: State of Matter - Liquefaction of Gases
Correct Answer: D) It cannot be liquefied at any value of P and T
- In the context of the kinetic theory of gases, an ideal gas is characterized by the absence of intermolecular or interatomic forces.
- Such a system is understood to exist solely as a gas.
- At very low pressures and sufficiently high temperatures, real systems approach the behavior of an ideal gas, where the attractive intermolecular forces are overcome.
- The non-existence of attractive forces and negligible volume of an ideal gas implies it cannot be liquefied under any temperature and pressure conditions.
- Therefore, the correct answer is D), "It cannot be liquefied at any value of P and T".
Question 27:
What are the units of the van der Waals constant "a"?
Topic: Gas Laws - Van der Waals Constant
Correct Answer: A) atm dm6/mol2 & Nm4/mol2
- The van der Waals constant "a" is an essential component of the van der Waals equation that accounts for interactions between gas particles.
- The units of the constant "a" are crucial for maintaining the integrity of this equation.
- Considering the physical parameters involved, the units for "a" are atm dm6/mol2 and Nm4/mol2.
- Therefore, the correct answer is A), "atm dm6/mol2 & Nm4/mol2".
Question 28:
If the rate of diffusion of hydrogen is 8 times that of a gas X2, what is the molecular weight of X2?
Topic: Gas Laws - Rate of Diffusion
Correct Answer: B) 128
- The rate of diffusion of gases is inversely proportional to the square root of their molar masses, according to Graham's law of diffusion.
- If the rate of diffusion of hydrogen is 8 times that of a gas X2, the molar mass of X2 must be 64 times that of hydrogen (since 8 squared equals 64).
- Given the molar mass of hydrogen is approximately 1, the molar mass of X2 must be 64 times this, which equals 64.
- Therefore, the correct answer is B), "128".