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BITSAT Ideal Solutions — practice questions

Explore 71 free Ideal Solutions questions in BITSAT Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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Ideal Solutions questions and exercises with answers

Showing questions 1–30 of 71.

Colligative properties of a dilute solution depend on:Read the answer and worked solution →$36$ g of glucose ($M = 180$ g/mol) is dissolved in $200$ g of water. The molality of the solution is:Read the answer and worked solution →The van't Hoff factor $i$ for a $0.01$ M aqueous solution of NaCl, assuming complete dissociation, is approximately:Read the answer and worked solution →Molarity M is defined as:Read the answer and worked solution →Molality m is defined as:Read the answer and worked solution →Mole fraction x_A is:Read the answer and worked solution →Raoult's law for an ideal solution (one component A in solvent S) is:Read the answer and worked solution →Colligative properties depend on:Read the answer and worked solution →What is the molarity of a solution containing 5.85 g of NaCl (M.W. = 58.5) in 250 mL of solution?Read the answer and worked solution →Boiling point elevation: ΔT_b = K_b × m. For 1 molal aqueous urea (K_b = 0.52 K kg/mol), ΔT_b equals:Read the answer and worked solution →Freezing point depression: ΔT_f = K_f × m. For 0.5 molal NaCl (assume full dissociation, K_f = 1.86), the depression is:Read the answer and worked solution →Vapour pressure of pure water at 25°C is 23.8 mm Hg. The vapour pressure of a solution with 18 g glucose (M.W. = 180) in 90 g water:Read the answer and worked solution →Osmotic pressure π = nRT/V (or CRT for molarity C). What is π for 0.1 M sugar solution at 27°C (R = 0.0821)?Read the answer and worked solution →The van't Hoff factor i for a strong electrolyte like CaCl2 (full dissociation) is:Read the answer and worked solution →In ideal solutions, ΔH_mix is:Read the answer and worked solution →Mass percentage (w/w) of a solution: 12 g sugar in 100 g of solution is:Read the answer and worked solution →Two solutions are isotonic if:Read the answer and worked solution →Maximum boiling azeotropes are formed by mixtures with:Read the answer and worked solution →Molality of a solution does not depend on:Read the answer and worked solution →For 0.5 m solutions of NaCl, KCl, and BaCl2, which gives largest ΔT_f?Read the answer and worked solution →Osmotic pressure of 0.1 M Glucose at 27°C is π_g. For 0.1 M NaCl at same T, the osmotic pressure is approximately:Read the answer and worked solution →The pKa of a weak acid HA is 4.75. Find pH of an equimolar mixture of HA and A⁻:Read the answer and worked solution →Solubility of N2 in water at 25°C is 6.8 × 10⁻⁴ mol/L at 1 atm partial pressure. By Henry's law, at 5 atm partial pressure of N2:Read the answer and worked solution →Two solutions A (0.1 M urea, π_A) and B (0.1 M NaCl, π_B). Water flows by osmosis:Read the answer and worked solution →A solution boils at 100.5°C (water at 100). If K_b = 0.52, molality is:Read the answer and worked solution →Mole fraction of solute in 18% glucose (180 g/mol) by mass in water:Read the answer and worked solution →Vapour pressure of pure water is 100 (arbitrary units). Add 1 mole non-volatile solute to 9 moles water. New vapour pressure is:Read the answer and worked solution →A solution is:Read the answer and worked solution →Mole fraction of solute x_B in a binary solution:Read the answer and worked solution →Molarity M is defined as:Read the answer and worked solution →

Worked practice questions

Colligative properties of a dilute solution depend on:

  1. The pressure only
  2. The temperature only
  3. The number of solute particles, not their nature
  4. The chemical nature of the solute
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Correct answer: C. The number of solute particles, not their nature

By definition, colligative properties (relative lowering of vapour pressure, boiling-point elevation, freezing-point depression, osmotic pressure) depend on how many solute particles are dissolved, not what those particles are. One mole of glucose and one mole of urea cause the same boiling-point elevation in 1 kg of water. With electrolytes like NaCl that dissociate into 2 ions, the effective particle count is multiplied by the van't Hoff factor $i$ (close to 2 for NaCl in dilute solution).

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$36$ g of glucose ($M = 180$ g/mol) is dissolved in $200$ g of water. The molality of the solution is:

  1. $0.5$ mol/kg
  2. $2.0$ mol/kg
  3. $0.1$ mol/kg
  4. $1.0$ mol/kg
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Correct answer: D. $1.0$ mol/kg

Moles of glucose: $\dfrac{36}{180} = 0.2$ mol. Mass of solvent in kilograms: $\dfrac{200}{1000} = 0.2$ kg. Molality: $m = \dfrac{0.2}{0.2} = 1.0$ mol/kg. Note the use of solvent mass (not solution mass) in the denominator: that distinction separates molality from molarity. For very dilute aqueous solutions the two are numerically close, but they diverge for concentrated solutions.

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The van't Hoff factor $i$ for a $0.01$ M aqueous solution of NaCl, assuming complete dissociation, is approximately:

  1. $1$
  2. $0.5$
  3. $2$
  4. $3$
Show answer and solution

Correct answer: C. $2$

NaCl dissociates in water: $\mathrm{NaCl} \rightarrow \mathrm{Na^+} + \mathrm{Cl^-}$. One formula unit produces two particles in solution. Van't Hoff factor $i = \dfrac{\text{actual moles of particles}}{\text{moles of solute formula units}}$. For complete dissociation of NaCl, $i = 2$. In reality, ion pairing slightly reduces $i$ below the theoretical value, especially at higher concentrations. At dilute $0.01$ M the assumption of complete dissociation is reasonable, and the experimental $i$ is close to $1.9$. The question asks for the theoretical value assuming complete dissociation, so 2 is the cleanest answer. Compare with $\mathrm{CaCl_2}$: dissociates into 3 ions, so $i = 3$ (option D) — common trap.

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More Chemistry topics

Chemical EquilibriumElectrochemistryCoordination CompoundsElectrochemical SeriesIdeal and Non-Ideal SolutionsNon-Ideal SolutionsReactions in Aqueous Solutionp-Block Elements