Explain what is observed
(i) when a beam of light is passed through a colloidal sol.
(ii) an electrolyte, NaCI is added to hydrated ferric oxide sol.
(iii) electric current is passed through a colloidal sol.
(i) Scattering of light by the colloidal particles takes place and the path of light becomes visible (Tyndall effect).
(ii) The positively charged colloidal particles of Fe(OH)3 get coagulated by the oppositely charged Cl– ions provided by NaCl.
(iii) On passing electric current, colloidal particles move towards the oppositely charged electrode where they lose their charge and get coagulated.
Assertion (A): Colloidal solutions show colligative properties.
Reason (R): Colloidal particles are large in size.
What type of solutions are formed on dissolving different concentrations of soap in water?
In the following questions, a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the following choices:
(a) Both Assertion and Reason are correct and the Reason is the correct explanation for Assertion.
(b) Both Assertion and Reason arc correct but Reason is not the correct explanation for Assertion.
(c) Assertion is correct but Reason is incorrect.
(d) Both Assertion and Reason are incorrect.
(e) Assertion is incorrect but Reason is correct
Assertion (A): An ordinary filter paper impregnated with collodion solution stops the flow of colloidal particles.
Reason (R): Pore size of the filter paper becomes more than size of colloidal particle.
A colloid is formed by adding FeCl3 in excess of hot water. What will happen if excess sodium chloride is added to this colloid?
Explain what is observed
(i) when a beam of light is passed through a colloidal sol.
(ii) an electrolyte, NaCI is added to hydrated ferric oxide sol.
(iii) electric current is passed through a colloidal sol.
Give an example where physisorption changes to chemisorption with rise in temperature. Explain the reason for change.
Why is it essential to wash the precipitate with water before estimating it quantitatively?
What are lyophilic and lyophobic sols? Give one example of each type. Why are hydrophobic sols easily coagulated?
Which of the following phenomenon occurs when a chalk stick is dipped in ink?
(a) Adsorption of coloured substance
(b) Adsorption of solvent
(c) Absorption and adsorption both of solvent
(d) Absorption of solvent.
Which of the following phenomenon occurs when a chalk stick is dipped in ink?
(a) Adsorption of coloured substance
(b) Adsorption of solvent
(c) Absorption and adsorption both of solvent
(d) Absorption of solvent.
H2 gas is adsorbed on activated charcoal to a very little extent in comparison
to easily liquefiable gases due to
(a) very strong van der Waals interaction
(b) very weak van der Waals forces
(c) very low critical temperature
(d) very high critical temperature.
In a reaction, catalyst changes
(a) physically (b) qualitatively
(c) chemically (d) quantitatively
Assertion (A): Detergents with low CMC are more economical to use. Reason (R): Cleansing action of detergents involves the formation of micelles. These are formed when the concentration of detergents becomes equal to CMC.
What is the role of adsorption in froth floatation process used especially for concentration of sulphide ores?
Distinguish between the meaning of the terms adsorption and absorption. Give one example of each.
Match the types of colloidal systems given in Column I with the name given in Column II.
Which of the following statements are correct?
(a) Mixing two oppositely charged sols neutralizes their charges and stabilizes the colloid.
(b) Presence of equal and similar charges on colloidal particles provides stability to the colloids.
(c) Any amount of dispersed liquid can be added to emulsion without destabilizing it.
(d) Brownian movement stabilizes sols.
Which phenomenon occurs when an electric field is applied to a-colloidal solution and electrophoresis is prevented?
(a) Reverse osmosis takes place.
(b) Electroosmosis takes place.
(c) Dispersion medium begins to move.
(d) Dispersion medium becomes stationary.
Assertion (A): Colloidal solutions do not show Brownian motion.
Reason (R): Brownian motion is responsible for stability of sols.
Arrange the following diagrams in correct sequence of steps involved in the mechanism of catalysis, in accordance with modem adsorption theory.
Which of the following options are correct?
(a) Micelle formation by soap in aqueous solution is possible at all temperatures.
(b) Micelle formation by soap in aqueous solution occurs above a particular concentration.
(c) On dilution of soap solution micelles may revert to individual ions.
(d) Soap solution behaves as a normal strong electrolyte at all concentrations.
What happens when a lyophilic sol is added to a lyophobic sol?
(a) Lyophobic sol is protected.
(b) Lyophilic sol is protected.
(c) Film of lyophilic sol is formed over lyophobic sol.
(d) Film of lyophobic sol is formed over lyophilic sol.
