CBSE 2026 Β· Region 2 Β· Set 1 Β· Q29 Β· 4 marks
Osmosis is a process by which the molecules of a solvent pass from a solution of low solute concentration to a solution of high solute concentration through a semi-permeable membrane. Osmotic pressure is a colligative property. When the applied pressure on a solution exceeds its osmotic pressure, reverse osmosis occurs. When two solutions are separated by a semipermeable membrane and they have same osmotic pressure they are said to be isotonic. Of the two solutions separated by a semipermeable membrane, if one is a lower osmotic pressure, it is said to be hypotonic relative to the second solution. If it has a higher osmotic pressure, than the second solution, it is said to be hypertonic relative to the second solution. The osmotic pressure associated with the fluid inside the blood cell is equivalent to that of $\displaystyle 0.9$% (mass/volume) sodium chloride solution called normal saline solution and it is safe to inject intravenously. Osmotic pressure is vital in daily life and nature. It helps in explain, why IV fluids match blood's osmotic pressure, its also the principle behind food preservation using salt or sugar.(a)Calculate the amount of $\displaystyle \mathrm{CaCl}_{2}(\mathrm{i}=2.59)$ dissolved in $\displaystyle 2.46$ litre of water such that its osmotic pressure is $\displaystyle 0.70$ atm at $\displaystyle 27$Β°C. [Given : $\displaystyle \mathrm{R}=0.082 \mathrm{~L}$ atm $\displaystyle \mathrm{K}^{-1} \mathrm{~mol}^{-1}$, molar mass of $\displaystyle \mathrm{CaCl}_{2}=111 \mathrm{~g} \mathrm{~mol}^{-1}$ ]When raisins are kept in water, they get swollen. Name the phenomenon involved in this process.Why osmotic pressure is more advantageous than other colligative properties?(c)Which phenomenon is responsible for desalination of sea water ?
Osmosis is a process by which the molecules of a solvent pass from a solution of low solute concentration to a solution of high solute concentration through a semi-permeable membrane. Osmotic pressure is a colligative property. When the applied pressure on a solution exceeds its osmotic pressure, reverse osmosis occurs. When two solutions are separated by a semipermeable membrane and they have same osmotic pressure they are said to be isotonic. Of the two solutions separated by a semipermeable membrane, if one is a lower osmotic pressure, it is said to be hypotonic relative to the second solution. If it has a higher osmotic pressure, than the second solution, it is said to be hypertonic relative to the second solution. The osmotic pressure associated with the fluid inside the blood cell is equivalent to that of $\displaystyle 0.9$% (mass/volume) sodium chloride solution called normal saline solution and it is safe to inject intravenously. Osmotic pressure is vital in daily life and nature. It helps in explain, why IV fluids match blood's osmotic pressure, its also the principle behind food preservation using salt or sugar.
(a)
Calculate the amount of $\displaystyle \mathrm{CaCl}_{2}(\mathrm{i}=2.59)$ dissolved in $\displaystyle 2.46$ litre of water such that its osmotic pressure is $\displaystyle 0.70$ atm at $\displaystyle 27$Β°C. [Given : $\displaystyle \mathrm{R}=0.082 \mathrm{~L}$ atm $\displaystyle \mathrm{K}^{-1} \mathrm{~mol}^{-1}$, molar mass of $\displaystyle \mathrm{CaCl}_{2}=111 \mathrm{~g} \mathrm{~mol}^{-1}$ ]
When raisins are kept in water, they get swollen. Name the phenomenon involved in this process.
Why osmotic pressure is more advantageous than other colligative properties?
(c)
Which phenomenon is responsible for desalination of sea water ?
Marking-scheme solution
(a)
Ξ = ππΆRT = π π
ππ΅
ππ΅ Γ
π R T
$\displaystyle 0.70$ atm = $\displaystyle 2.59$ X
ππ΅
$\displaystyle 111$ g molβ$\displaystyle 1$π
2.$\displaystyle 46$ L π $\displaystyle 0.082$ L atmKβ1molβ$\displaystyle 1$ π $\displaystyle 300$ K
ππ΅= $\displaystyle 0.70$ X111 X $\displaystyle 2.46$
2.$\displaystyle 59$ X $\displaystyle 0.082$ X $\displaystyle 300$
WB = 3g
Osmosis
Unlike other colligative properties, its magnitude is large even for very dilute
solutions / It is measured at room temperature. / Molarity is used instead of molality.
(c)
Reverse osmosis
SolutionsColligative Properties and Determination of Molar MassApplycase_studymedium
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CBSE Class 12 Chemistry past-paper question from the 2026board exam, with the answer as CBSEβs own marking scheme gives it. Where our answers come from.