Title DPP-5 SOLUTION.pdf ✅

CLASS : XIth SUBJECT : CHEMISTRY DATE : DPP No. : 5 2 (a) Soaps, surfactants, polymers and finely divided metal oxides and hydroxides are emulsifiers. 3 (b) The phenomenon of change of colloidal state to suspension state is called flocculation of colloidal solution. According to Hardy-Schulze rule, the flocculating power of electrolyte increases with valency of ion of electrolyte. 4 (c) Organic sols are usually lyophilic. 5 (b) A solid may be lyophilic or lyophobic. 6 (c) Adsorption theory involves adsorption of gas on solids. 7 (b) Transition metals are more effective catalyst on account of their larger surface area and half filled nature of penultimate d⎯subshells. 8 (d) Emulsion are the colloidal solutions in which both the dispersed phase and the dispersion medium are liquids. A good example of an emulsion is milk in which fat globules are dispersed in water. 9 (b) H3PO4, acetamide acts as negative catalyst for decomposition of H2O2. 10 (c) Zeolites are used to make soft water from hard water as well as catalyst in petrochemical industry due to their shape selective nature or activity because of different pore sizes and cavity sizes on their surface. 11 (c) Starch is an example of lyophilic (water loving) colloidal solution. Lyophilic colloids are those colloids which form colloidal solution in contact with water. 12 (d) Poisoners are adsorbed on active centres either physically (temporary poisoning) or Topic :- SURFACE CHEMISTRY Solutions
chemically (permanent poisoning). 13 (a) x m = P(at constant T) and x m decrease with T at constant P. 14 (b) Heterogeneous gases are adsorbed to greater extent 15 (b) Fog is an example of aerosols i.e., it is a colloidal solution of liquid in gas, where liquid is dispersed phase and gas is dispersion medium. 16 (c) A catalyst increases the rate of forward and rate of backward reaction to attain equilibrium earlier. 17 (a) Since ferric ions can coagulate negatively charged blood solution, therefore ferric chloride may be applied to stop bleeding 18 (a) The formation of colloid from suspension is called peptisation. The process of converting a precipitate (suspension) into colloidal particles by adding suitable electrolyte is known as peptisation. 19 (c) Mist is liquid dispersed in gas. 20 (b) A catalyst alter the nature of chemical reaction by lowering the activation energy of the reactants and products
ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. A A B C B C B D B C Q. 11 12 13 14 15 16 17 18 19 20 A. C D A B B C A A C B