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Solution and Colloids MCQs for MDCAT Practice

Chemistry section, Solution and Colloids chapter. Up to eight free sample questions, each with the correct answer and a worked explanation. The full chapter opens in the app.

The bank has 505 active questions on this chapter. Your first 500 practice attempts are free, and every attempt includes a worked explanation.

  1. Question 1
    The solubility of NH4NO3, HgCl2 & AgBr at 20oC in 100 g water is 192 g, 6.5 g & 8.4x10-4 g respectively. It means that among these three solutes:
    • HgCl2 has the greatest covalent nature
    • AgBr has the greatest covalent nature (correct answer)
    • NH4NO3 & AgBr have equal covalent nature
    • All have equal covalent nature
    Correct answer: B
    Low solubility in water often indicates significant covalent character in ionic compounds. AgBr's extremely low solubility suggests it's the most covalent among the options.
  2. Question 2
    Pure water is
    • poor conductor (correct answer)
    • very good conductor
    • slight conductance
    • neutral
    Correct answer: A
    Pure water exhibits extremely low electrical conductivity due to minimal ion formation, making it a poor conductor.
  3. Question 3
    A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of 290 mm at 300 K. The vapour pressure of propyl alcohol is 200 mm. If the mole fraction of ethyl alcohol is 0.6, its vapour pressure (in mm) at the same temperature will be:
    • 360
    • 350 (correct answer)
    • 300
    • 700
    Correct answer: B
    Apply Raoult's Law to calculate the vapor pressure of a component in an ideal solution given total vapor pressure and mole fractions.
  4. Question 4
    Water molecules surround more around?
    • Complex ion
    • Simple ion
    • Negative ion
    • Positive ion (correct answer)
    Correct answer: D
    The extent of hydration, or water molecules surrounding an ion, depends on the ion's charge density. Positive ions with higher charge density attract water more strongly.
  5. Question 5
    At high altitudes, the boiling point of water decreases because:
    • Atmospheric pressure is low (correct answer)
    • Temperature is low
    • Atmospheric pressure is high
    • None of the above
    Correct answer: A
    Boiling point decreases at high altitudes because lower atmospheric pressure reduces the energy needed for water molecules to escape into the gaseous phase.
  6. Question 6
    The molal elevation constant of water is 0.51. The boiling point of a 0.1 molal aqueous NaCl solution is nearly:
    • 100.05C
    • 100.1C (correct answer)
    • 100.2C
    • 101.0C
    Correct answer: B
    Calculate the boiling point elevation of a NaCl solution using the molal elevation constant, accounting for van't Hoff factor.
  7. Question 7
    What is the molality of a solution having 30g of urea in 2000g of water?
    • 1 molal
    • 0.75 molal
    • 0.5 molal
    • 0.25 molal (correct answer)
    Correct answer: D
    Calculate molality: moles of solute divided by kilograms of solvent. This question tests understanding of molality as a concentration unit.
  8. Question 8
    The colloids formed by lyophilic molecules are:
    • Irreversible
    • Stable (correct answer)
    • Cannot store
    • All of the above
    Correct answer: B
    Lyophilic colloids, formed via direct interaction, exhibit strong intermolecular forces, leading to inherent stability against coagulation.

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