Free Evaporation, Boiling Point and Vapour Pressure MCQs with Answers
107 Evaporation, Boiling Point and Vapour Pressure MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Evaporation is the escape of higher-energy molecules from a liquid surface, while vapour pressure is the pressure exerted by vapour in equilibrium with that liquid. The topic distinguishes evaporation from boiling and relates both to temperature, intermolecular forces, surface area, atmospheric pressure and the boiling point.
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107 questions · page 5 of 6
- A. H bonding
- B. Dipole forces
- C. London forces
- D. Debye forces
Explanation: The most important type of intermolecular force for noble gases is London dispersion forces.
Correct answer: London forces- A. Surface area
- B. Temperature
- C. External pressure
- D. Humidity
Explanation: The rate of evaporation does not depend on external pressure because the process of evaporation does not involve the compression or…
Correct answer: External pressure- A. Diethyl ether
- B. Chloroform
- C. Carbon tetrachloride
- D. Water
Explanation: The boiling point of a substance is a measure of the strength of the intermolecular forces between the molecules of the substance.
Correct answer: Water- A. Raised than the normal
- B. Lower than the normal
- C. Lower than the freezing point
- D. All of these options are correct
Explanation: The trapped steam increases the atmospheric pressure inside the cooker by 15 pounds per square inch (psi) or 15 pounds above-normal…
Correct answer: Raised than the normal- A. n-pentane
- B. Iso-pentane
- C. Neo-pentane
- D. All same
Explanation: The intermolecular forces in n-pentane are STRONGER than those in isopentane and neopentane.
Correct answer: n-pentane- A. Increase
- B. Decrease
- C. Constant
- D. Unknown
Explanation: When a liquid is heated, the kinetic energy of its molecules increases and hence the temperature also increases.
Correct answer: Constant87. The amount of heat required to form vapors of one mole of a liquid at its boiling point is called?
- A. Molar heat of fusion
- B. Molar heat of vapourization
- C. Molar heat of sublimation
- D. Molar heat of Evaporation
Explanation: Option A is incorrect since the molar heat of fusion is the amount of heat required to convert one mole of a substance from the solid to…
Correct answer: Molar heat of vapourization88. Boiling of dilute HCl acid does not increase its concentration beyond 22 percent because HCl acid:
- A. Is very volatile
- B. Highly soluble in water
- C. Forms boiling mixture
- D. Forms saturated at this concentration
Explanation: When the concentration of HCl gas in water is 22.2% by weight, it forms a constant boiling mixture.At this concentration, if dilute HCl is…
Correct answer: Forms boiling mixture- A. Acetone
- B. Ethanol
- C. Water
- D. Ethylene glycol
Explanation: Acetone evaporates much faster than water, even though its molecular mass is more than three times as much.
Correct answer: Acetone- A. Temperature
- B. Intermolecular forces
- C. Density of liquid
- D. Surface area of liquid
Explanation: Vapour pressure is independent of the surface area of liquid.
Correct answer: Surface area of liquid- A. Physical state of matter
- B. Intermolecular forces
- C. Surface area
- D. Temperature
Explanation: Option B: A liquid's vapor pressure is directly related to the intermolecular forces present between its molecules.
Correct answer: Surface area- A. Endothermic reaction
- B. Exothermic reaction
- C. Chemical reaction
- D. None of the above
Explanation: Evaporation does not involve the conversion of one chemical species to another (the chemical species is water throughout).
Correct answer: Endothermic reaction- A. Mercury pressure
- B. Glass pressure
- C. Atmospheric pressure
- D. Container pressure
Explanation: Vapor pressure is measured by taking the difference in liquid pressure and atmospheric pressure.Note: Total pressure (also called liquid…
Correct answer: Atmospheric pressure- A. Glycerol
- B. Isopentane
- C. Ethanol
- D. Both Options A and C are correct
Explanation: Glycerol have lower vapor pressure compared to isopentane and ethanol. Vapor pressure is a measure of the tendency of a substance to…
Correct answer: Glycerol- A. Sublimation
- B. Freezing
- C. Melting
- D. Condensation
Explanation: Evaporation is the process of a liquid changing into a gas phase. It occurs at the surface of the liquid.
Correct answer: Condensation- A. Decrease in external pressure increases the boiling point
- B. Increase in external pressure decreases the boiling point
- C. Increase in external pressure increases the boiling point
- D. None of these options are correct
Explanation: A pressure cooker is a closed container. The vapours of water formed are not allowed to escape.
Correct answer: Increase in external pressure increases the boiling point- A. Glycerol
- B. Isopentane
- C. Ethanol
- D. Both A and C
Explanation: Correct option is A. Vapor pressure depends upon the molecules that bond well and the forces of attraction of mercury metal atoms are…
Correct answer: Glycerol- A. Physical state of matter
- B. Intermolecular forces
- C. Temperature
- D. Both B and C
Explanation: The vapour pressure depends on two factors:1. Nature of liquid: The nature of liquid is explained on the basis of its intermolecular…
Correct answer: Both B and C- A. Surface phenomena is applicable.
- B. It causes cooling.
- C. Is exothermic.
- D. It is continous
Explanation: Molecules at the surface use enough energy to exceed vapor pressure and they escape in the form of gas in the air.
Correct answer: It causes cooling.- A. Concentration
- B. Ratio between the particles
- C. Vapour pressure
- D. Attraction between the phases
Explanation: It's the standard definition of a Freezing point. The freezing point is "the temperature at which the vapor pressure of the substance in…
Correct answer: Vapour pressure