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CBSE Chemistry Class 12 Sample Paper – SURFACE CHEMISTRY

MM : 25                                     TIME : 40 MIN.
1. Name the catalyst used in the Ostwald process for the manufacture of nitric acid .
2. What happens when a colloidal sol of Fe(OH)3 is mixed with that of As2S3 ?
3. How does alum helps in the purification of water with suspended impurities ?
4. Define gold number .
5. Why sky appears blue in the colour ?
6. Write down the difference between sols and emulsions.
7. What does activity and selectivity of catalyst means ? Explain.
8. What is CMC and Kraft temperature with respect to Micelles formation?
9. What is the difference between adsorption isotherm and adsorption isobar ?
10.In which of the following does adsorption takes place
(i) Silica gel placed in the atmosphere containing water .
(ii) Anhydrous CaCl2 placed in the atmosphere containing water .
11.Differentiate between multimolecular, macromolecular and associated colloids ?
12.Write short note on (a) Electrophoresis (b) Peptization .
13.Differentiate between (a) Physical and chemical adsorption (b) Lyophillic and Lyophobic colloids .


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CBSE Class 12 Chemistry Revision Test – Solutions

MM : 25                                             TIME : 40 MIN.
1. Two liquids A and B boil at 145oC respectively and 190oc respectively . Which of them has a higher vapour pressure at 80oc ?
2. Why is freezing point depression of 0.1 M sodium chloride solution nearly twice that of 0.1M glucose solution ?
3. Define the term molarity of the solution . State one disadvantage in using the molarity as the unit of concentration.
4. Define the term osmotic pressure . What is advantage of using osmotic pressure as compared to other colligative properties for the determination of molar masses of solutes in the solutions ?.
5. Non – ideal solutions exhibit either positive or negative deviation for Raoult’s law . What are these deviations and why are they caused ?
6. What mass of ethylene glycol (molar mass = 62g mol-1) must be added to 5.50 Kg of water to lower the freezing point of water to lower the freezing point of water from 00c to – 10 .0 0c ? [Kf for water = 1.86 K Kg mol-1 )
7. What concentration of nitrogen should be present in a glass of water at room temperature. Assume a temperature of 25oc a total pressure of 1 atmosphere and mole fraction of nitrogen in air of 0.78 (Kh for N2 = 8.42 x 10-7 M/mm Hg) .
8. The boiling point elevation of 0.30 g acetic acid in 100 g benzene is 0.0633 K . Calculate the molar mass of acetic acid from this data . What conclusion can you draw about the molecular state of the solute in the solution ? [Kb = 2.53 K Kg mol-1)
9. An antifreeze solution is prepared from 222.6 g of ethyleneglycol and 200 g of water . Calculate the molality of the solution . If density of this solution be 1.072gml-1 What will be the molarity of the solution?
10. Urea forms an ideal solution in water . Determine the vapour pressure of an aqueous solution containing 10% by mass of urea at 400c ( vapour pressure of water = 55.3 mm of Hg)
11. A 4% solution of sucrose is isotonic with 3% solution of an unknown organic substance . Calculate the molecular mass of unknown substance .


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