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.
(b, c) Micelle formation is possible only above critical micelle concentration and on dilution the micelles may form electrolytes.
Why is it essential to wash the precipitate with water before estimating it quantitatively?
Assertion (A): Colloidal solutions show colligative properties.
Reason (R): Colloidal particles are large in size.
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.
Why does the white precipitate of silver halide become coloured in the presence of dye eosin.
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.
What are lyophilic and lyophobic sols? Give one example of each type. Why are hydrophobic sols easily coagulated?
Distinguish between the meaning of the terms adsorption and absorption. Give one example of each.
What type of solutions are formed on dissolving different concentrations of soap in water?
Assertion (A): Colloidal solutions do not show Brownian motion.
Reason (R): Brownian motion is responsible for stability of sols.
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 Haber's process, hydrogen is obtained by reacting methane with steam in presence of NiO as catalyst. The process is known as steam reforming. Why is it necessary to remove CO when ammonia is obtained by Haber's process?
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.
Which of the following colloids cannot be coagulated easily?
(a) Lyophobic colloids (b) Irreversible colloids
(c) Reversible colloids (d) Lyophilic colloids
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.
Give an example where physisorption changes to chemisorption with rise in temperature. Explain the reason for change.
Assertion (A): Coagulation power of Al3+ is more than Na+
Reason (R): Greater the Valency of the flocculating ion added, greater is its power to cause precipitation (Hardy-Schulze rule).
What is the role of adsorption in froth floatation process used especially for concentration of sulphide ores?
Arrange the following diagrams in correct sequence of steps involved in the mechanism of catalysis, in accordance with modem adsorption theory.
An emulsion cannot be broken by and
(a) heating
(b) adding more amount of dispersion medium
(c) freezing
(d) adding emulsifying agent
