The geometrical shape adopted by an ionic crystal depends mainly on the ____
Correct answer C. ratio of the radius of the cation to that of the anion
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MDCAT ECAT Chemistry MCQs
Page 34 of MDCAT ECAT Chemistry 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
For a crystal with r(Na⁺) = 95 pm and r(Cl⁻) = 181 pm, what coordination number does the radius ratio predict?
Correct answer B. 6
Why does solid NaCl not conduct electricity but molten NaCl does?
Correct answer A. Ions are fixed in the solid lattice but free to move in the melt
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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
In ice, how many water molecules surround each water molecule through hydrogen bonds?
Correct answer A. 4
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
When a liquid is placed in a closed container, what is true once a constant vapour pressure is reached?
Correct answer B. Rate of evaporation equals rate of condensation
Why is ethanol completely miscible with water?
Correct answer C. Ethanol molecules form hydrogen bonds with water molecules
Why does water boil below 100 °C at a hill station such as Murree?
Correct answer A. Atmospheric pressure there is lower than at sea level
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How does the surface tension of a liquid change as its temperature rises?
Correct answer A. It decreases
Which statement correctly distinguishes evaporation from boiling?
Correct answer C. Evaporation occurs at all temperatures from the surface; boiling occurs at a fixed temperature throughout the liquid
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
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Why does food cook faster in a pressure cooker?
Correct answer B. The increased pressure raises the boiling point of water
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 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