LiquidsHydrogen Bonding in Biomolecules121Choose the best answerThe two strands of a DNA double helix are held together mainly by:AHydrogen bondingBIonic bondingCMetallic bondingDCovalent bonds between the two strands Like 0 Discuss 0Share
LiquidsBoiling Point and External Pressure122Choose the best answerIf the external pressure on a liquid is reduced from 760 mmHg to 50 mmHg, its boiling point will:ADecreaseBRemain unchangedCIncreaseDBecome independent of pressure Like 0 Discuss 0Share
LiquidsHeat of Vaporization and Intermolecular Forces123Choose the best answerLiquids with strong dipole–dipole attractions generally have:ANegligible heat of vaporizationBHigh heat of vaporizationCVery low heat of vaporizationDZero heat of vaporization Like 0 Discuss 0Share
LiquidsAnomalous Behaviour of Water124Choose the best answerWater becomes less dense when it freezes because:AAn open hydrogen-bonded structure containing empty spaces formsBIonic bonds are formedCO–H bonds disappearDMolecular mass decreases Like 0 Discuss 0Share
LiquidsLiquid–Vapour Dynamic Equilibrium125Choose the best answerIn a closed container at dynamic equilibrium:AEvaporation stopsBCondensation stopsCRate of evaporation equals rate of condensationDVapour pressure becomes zero Like 0 Discuss 0Share