How much heat is needed to vaporise 9.0 g of water at its boiling point (ΔHvap = 40.7 kJ mol⁻¹, H₂O = 18 g mol⁻¹)?
Correct answer D. 20.4 kJ
Topic / 40 questions
Liquids MCQs
Page 2 of Liquids multiple-choice questions with answers. Tap an option to check yourself.
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- Gases 40
- Liquids 40
- Solids 40
- Chemical Equilibrium 40
- Reaction Kinetics 40
- Thermochemistry and Energetics 40
- Electrochemistry 40
- Fundamental Concepts of Chemistry 40
- Atomic Structure 39
- Chemical Bonding 39
- Alcohols and Phenols 38
- Industrial Chemistry 37
- Aldehydes and Ketones 37
- Alkyl Halides 37
- s- and p-Block Elements 37
- Chemistry of Hydrocarbons 36
- Fundamental Principles of Organic Chemistry 36
- Carboxylic Acids 36
- Transition Elements 35
- Macromolecules 35
In ice, how many water molecules surround each water molecule through hydrogen bonds?
Correct answer A. 4
What happens to the volume of a fixed mass of water as it is cooled from 4 °C to 0 °C?
Correct answer D. It increases
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Why does water have a higher boiling point than HF, even though fluorine is more electronegative than oxygen?
Correct answer B. Each water molecule can form more hydrogen bonds than an HF molecule
Why does evaporation cause cooling of the remaining liquid?
Correct answer B. Molecules with high kinetic energy escape, lowering the average kinetic energy
Which change does NOT increase the rate of evaporation of a liquid?
Correct answer A. Increasing the strength of intermolecular forces
The vapour pressure of a pure liquid depends on ____
Correct answer A. its temperature and the nature of the liquid
The boiling point of a liquid is the temperature at which ____
Correct answer B. its vapour pressure equals the external pressure
Why does food cook faster in a pressure cooker?
Correct answer B. The increased pressure raises the boiling point of water
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At its normal boiling point, what is the vapour pressure of a liquid?
Correct answer C. 760 mm Hg
At 20 °C, which liquid has the highest vapour pressure?
Correct answer B. Diethyl ether
Among the hydrides H₂O, H₂S, H₂Se and H₂Te, which has the highest boiling point?
Correct answer D. H₂O
Why does NH₃ have a much higher boiling point than PH₃?
Correct answer D. NH₃ molecules are linked by hydrogen bonds
Which of the following is the strongest individual hydrogen bond?
Correct answer C. F–H···F
Which compound cannot form hydrogen bonds between its own molecules?
Correct answer B. H₂S
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At what temperature does liquid water have its maximum density?
Correct answer D. 4 °C
Why does ice float on liquid water?
Correct answer C. Hydrogen bonding gives ice an open cage structure with empty spaces
How does aquatic life survive in a lake whose surface has frozen in winter?
Correct answer B. Water at 4 °C is densest and stays at the bottom, below the floating ice
According to the kinetic molecular theory, liquids have a definite volume but no definite shape because their molecules ____
Correct answer B. are close together but can slide past one another
Why is diffusion much slower in liquids than in gases?
Correct answer C. Liquid molecules are close together and attract each other strongly