Tiêu đề DPP-2 SOLUTION.pdf ✅

CLASS : XIth SUBJECT : CHEMISTRY DATE : DPP No. : 2 1 (c) Higher the gold number, lesser will be the protective power of colloid. 2 (d) Gold number is the amount of substance in milligram that is required to prevent coagulation of 10 cm3 of gold sol by addition of 1 mL of 10% NaCl solution. Convert 0.025 g into milligram = 25 0.025 g starch = 0.025 × 1000 = 25 mg Thus, the gold number of starch = 25 3 (c) 50 mL of 1 M oxalic acid [(COOH)2 .2H2O] = 50 millimol = 0.050 mol = 0.050 × 126 g = 6.3 g 50 mL of 0.5 M oxalic acid = 3.15 g ∴ Oxalic acid asorbed on 0.5 g charcoal = 6.3 ― 3.15 = 3.15 g ∴ Amount of oxalic acid adsorbed per gram of charcoal = 3.19 0.5 = 6.3 4 (c) Colloidal solutions are heterogeneous in nature. 5 (c) The scattering ∝ 1 λ 4. Thus, scattering of blue light (shorter wavelength) is more. 6 (a) It is the definition of synerisis, a property of gel. 7 (c) Solid aerosol involves solid dispersed in gas, e.g., smoke, storm, etc. 8 (c) Negative colloid is coagulated by positive ion or vice-versa. Greater the valency of coagulating ion, greater will be coagulating ion, greater will be coagulating power. Topic :- SURFACE CHEMISTRY Solutions
(a)ZnSO4→Zn2+ + SO2― 4 (b)Na3PO4→3Na+ + PO3― 4 (c)AlCl3→Al3+ + 3Cl― (d)K4 [Fe(CN)6 ]→4K + + [Fe(CN)6 ] 4― Since, in AlCl3, the valency of positive ion (coagulation ion) is highest, it is the most powerful coagulating agent among the given to coagulate the negative colloid. 9 (b) C2H5OH acts as negative catalyst for oxidation of CHCl3. 11 (a) Catalyst affects only activation energy. It brings down activation energy of reaction. Catalyst does not affect equilibrium constant, reaction entropy and reaction enthalpy. 12 (b) The blue colour of sky is due to Tyndall effect i.e., the colloidal particles adsorb light, become self luminous and then scatter light of different wavelengths in all possible directions. 13 (d) Egg albumin is organic sols and organic sols are usually lyophilic. 14 (a) In chemical adsorption, unimolecular layer is formed over the surface of adsorbent 15 (a) Blood is purified by dialysis method 16 (a) Berzelius used the term for the first time. 17 (d) The sky looks blue due to scattering of light. 18 (a) Fermentation of starch is enzyme catalysed reaction, (C6H10O5 )n Diastase C12H22O11 19 (c) The efficiency of a catalyst depends upon the size of particles 20 (c) Adsorption of gases increases with pressure, decreases with temperature.
ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. C D C C C A C C B A Q. 11 12 13 14 15 16 17 18 19 20 A. A B D A A A D A C C