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.
Statements (b) and (c) are correct whereas statements
(a) and (d) are incorrect.
(a) Process of precipitating colloidal sol is known as
(b) Concentration of colloidal solutions is small due to large
molar mass and thus, their colligative properties are very
small compared to true solutions. Hence, these solution
freezes at higher temperature.
(c) Micelles are formed at the critical micelle concentration
(CMC) which depends to temperature.
(d) Micelles and macromolecular colloids are two different
types of colloid.
JEE Advanced 2020 Paper 1 Offline
MCQ (More than One Correct Answer)
The cubic unit cell structure of a compound containing cation M and anion X is shown below. When compared to the anion, the cation has smaller ionic radius. Choose the correct statement(s).
The empirical formula of the compound is MX.
The cation M and anion X have different coordination geometries.
The ratio of M$$-$$X bond length of the cubic unit cell edge length is 0.866.
The ratio of the ionic radii of cation M to anion X is 0.414.
The correct statement(s) about surface properties is (are)
Adsorption is accompanied by decrease in ethalpy and decrease in entropy of the system
The critical temperatures of ethane and nitrogen are $$563$$ $$K$$ and $$126$$ $$K,$$ respectively. The adsorption of ethane will be more than that of nitrogen on same amount of activated charcoal at a given temperature
Cloud is an emulsion type of colloid in which liquid is dispersed phase and gas is dispersion medium
Brownian motion of colloidal particles does not depend on the size of the particles but depends on viscosity of the solution
Option (A) : Correct. Adsorption is a surface phenomenon in which the concentration of the adsorbate increases only on the surface. It is always accompanied by a decrease in the entropy ($$\Delta$$S). Since adsorption is an exothermic process, the enthalpy change ($$\Delta$$H) of the system is also negative.
Option (B) : Correct. Easily liquefiable gases, that is, gases with high critical temperatures, are more readily adsorbed because van der Waals forces are stronger near the critical temperature. Thus, the adsorption of ethane will be more than that of nitrogen.
Option (C) : Cloud is an aerosol in which liquid is dispersed phase and gas is dispersion medium. Whereas, emulsion is liquid in liquid colloidal system.
Option (D) : Incorrect. Brownian movement varies with the size of the particles and viscosity of the solution. Smaller particles with lower viscosity show faster movement.
JEE Advanced 2016 Paper 2 Offline
MCQ (More than One Correct Answer)
The CORRECT statement(s) for cubic close packed (ccp) three dimensional structure is (are) :
The number of the nearest neighbours of an atom present in the topmost layer is 12
The efficiency of an atom packing is 74%
The number of octahedral and tetrahedral voids per atom are 1 and 2, respectively
The unit cell edge length is $$2 \sqrt 2$$ times the radius of the atom
Coordination number cannot be 12, for any atom in the topmost layer, as there is no layer above it. Thus, each atom is in contact with six atoms in the same layer and three atoms from the layer below it.