The correct statement(s) related to colloids is(are)
The process of precipitating colloidal sol by an electrolyte is called peptization.
Colloidal solution freezes at higher temperature than the true solution at the same concentration.
Surfactants form micelle above critical micelle concentration (CMC). CMC depends on temperature.
Micelles are macromolecular colloids.
The Correct Option is B, C
Solution and Explanation
The statement is False:
Peptization refers to the process of converting a precipitate into a colloidal sol, not the other way around. Peptization is the dispersion of fine particles into a colloidal form by adding a suitable dispersing agent (often a small amount of electrolyte). This is different from the process of coagulation, where a colloidal sol is converted into a precipitate. Therefore, the given statement is incorrect.
The statement is True:
Colloidal solutions do exhibit colligative properties, but with a slight difference from true solutions. For example, a colloidal solution may show a higher freezing point depression or lower vapor pressure than a true solution, as the dispersed particles in the colloidal system can affect the overall behavior of the solvent. However, the statement claims that the freezing point is higher in colloidal solutions, which is inaccurate in terms of freezing point depression, but may be a misunderstanding of the phenomenon.
Note: The correct assertion should be that colloidal solutions show some effects of colligative properties, but their freezing point depression is often less than that of true solutions at the same concentration due to the large size of the dispersed particles.
The statement is True:
Surfactants indeed form micelles above the critical micelle concentration (CMC). The CMC is the concentration at which surfactant molecules aggregate to form micelles, and it depends on various factors, including temperature. As the temperature increases, the CMC can change, generally decreasing as temperature increases because the surfactant molecules become more energetically favorable to form micelles at lower concentrations.
Therefore, the statement about micelles and their dependence on temperature is correct.
The statement is False:
Micelles are not macromolecular colloids. Macromolecular colloids refer to large molecules such as proteins or polymers that are naturally colloidal in nature. On the other hand, micelles are associated colloids, formed by the aggregation of surfactant molecules (amphiphilic molecules) in a solvent, where the hydrophobic tails aggregate inward and the hydrophilic heads face outward. This aggregation occurs only above the critical micelle concentration (CMC). Therefore, the statement about micelles being macromolecular colloids is false.
Top Questions on Solutions
According to the generally accepted definition of the ideal solution there are equal interaction forces acting between molecules belonging to the same or different species. (This is equivalent to the statement that the activity of the components equals the concentration.) Strictly speaking, this concept is valid in ecological systems (isotopic mixtures of an element, hydrocarbons mixtures, etc.). It is still usual to talk about ideal solutions as limiting cases in reality since very dilute solutions behave ideally with respect to the solvent. This law is further supported by the fact that Raoult’s law empirically found for describing the behaviour of the solvent in dilute solutions can be deduced thermodynamically via the assumption of ideal behaviour of the solvent.
Answer the following questions:
(a) Give one example of miscible liquid pair which shows negative deviation from Raoult’s law. What is the reason for such deviation?
(b) (i) State Raoult’s law for a solution containing volatile components.
OR
(ii) Raoult’s law is a special case of Henry’s law. Comment.
(c) Write two characteristics of an ideal solution.- A solution of glucose (molar mass = 180 g mol\(^{-1}\)) in water has a boiling point of 100.20°C. Calculate the freezing point of the same solution. Molal constants for water \(K_f\) and \(K_b\) are 1.86 K kg mol\(^{-1}\) and 0.512 K kg mol\(^{-1}\) respectively.
- Define Azeotrope. What type of Azeotrope is formed by negative deviation from Raoult's law? Give an example.
- Give reasons:
(a) Cooking is faster in a pressure cooker than in an open pan.
(b) On mixing liquid X and liquid Y, volume of the resulting solution decreases. What type of deviation from Raoult's law is shown by the resulting solution? What change in temperature would you observe after mixing liquids X and Y? - An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because __________
Questions Asked in JEE Advanced exam
Let $ a_0, a_1, ..., a_{23} $ be real numbers such that $$ \left(1 + \frac{2}{5}x \right)^{23} = \sum_{i=0}^{23} a_i x^i $$ for every real number $ x $. Let $ a_r $ be the largest among the numbers $ a_j $ for $ 0 \leq j \leq 23 $. Then the value of $ r $ is ________.
- JEE Advanced - 2025
- binomial expansion formula
- Consider the vectors $$ \vec{x} = \hat{i} + 2\hat{j} + 3\hat{k},\quad \vec{y} = 2\hat{i} + 3\hat{j} + \hat{k},\quad \vec{z} = 3\hat{i} + \hat{j} + 2\hat{k}. $$ For two distinct positive real numbers $ \alpha $ and $ \beta $, define $$ \vec{X} = \alpha \vec{x} + \beta \vec{y} - \vec{z},\quad \vec{Y} = \alpha \vec{y} + \beta \vec{z} - \vec{x},\quad \vec{Z} = \alpha \vec{z} + \beta \vec{x} - \vec{y}. $$ If the vectors $ \vec{X}, \vec{Y}, \vec{Z} $ lie in a plane, then the value of $ \alpha + \beta - 3 $ is ________.
Let $ y(x) $ be the solution of the differential equation $$ x^2 \frac{dy}{dx} + xy = x^2 + y^2, \quad x > \frac{1}{e}, $$ satisfying $ y(1) = 0 $. Then the value of $ 2 \cdot \frac{(y(e))^2}{y(e^2)} $ is ________.
- JEE Advanced - 2025
- Differential equations
The left and right compartments of a thermally isolated container of length $L$ are separated by a thermally conducting, movable piston of area $A$. The left and right compartments are filled with $\frac{3}{2}$ and 1 moles of an ideal gas, respectively. In the left compartment the piston is attached by a spring with spring constant $k$ and natural length $\frac{2L}{5}$. In thermodynamic equilibrium, the piston is at a distance $\frac{L}{2}$ from the left and right edges of the container as shown in the figure. Under the above conditions, if the pressure in the right compartment is $P = \frac{kL}{A} \alpha$, then the value of $\alpha$ is ____
- JEE Advanced - 2025
- Thermodynamics
- The total number of real solutions of the equation $$ \theta = \tan^{-1}(2 \tan \theta) - \frac{1}{2} \sin^{-1} \left( \frac{6 \tan \theta}{9 + \tan^2 \theta} \right) $$ is
(Here, the inverse trigonometric functions $ \sin^{-1} x $ and $ \tan^{-1} x $ assume values in $[-\frac{\pi}{2}, \frac{\pi}{2}]$ and $(-\frac{\pi}{2}, \frac{\pi}{2})$, respectively.)- JEE Advanced - 2025
- Inverse Trigonometric Functions
Concepts Used:
Types of Solutions
Solutions are homogeneous mixtures of two or more substances, where the solute is uniformly dispersed in the solvent. Solutions can be classified into several types based on their composition and properties.
- Gas solutions: These are solutions where gases are dissolved in other gases, such as oxygen and nitrogen in air.
- Liquid solutions: These are solutions where a liquid is dissolved in another liquid, such as ethanol in water.
- Solid solutions: These are solutions where a solid is dissolved in another solid, such as an alloy of copper and zinc.
- Aqueous solutions: These are solutions where water is the solvent, such as saltwater or sugar water.
- Concentrated solutions: These are solutions where a large amount of solute is dissolved in the solvent, resulting in a high concentration.
- Dilute solutions: These are solutions where a small amount of solute is dissolved in the solvent, resulting in a low concentration.
- Saturated solutions: These are solutions where the maximum amount of solute has been dissolved in the solvent at a given temperature and pressure.
- Supersaturated solutions: These are solutions where more solute has been dissolved in the solvent than is normally possible at a given temperature and pressure.
- Colloidal solutions: These are solutions where the size of the dispersed particles is between 1 and 1000 nanometers. These solutions have unique properties such as Brownian motion and Tyndall effect.
Understanding the different types of solutions is important for understanding their properties, behavior, and applications in various fields, such as chemistry, biology, and engineering.