Sample Paper 3 for Class XII

Unit : 5

Surface chemistry

M.M.20

  1. Out of CO and NH3 which is adsorbed on activated charcoal to large extent and why?                   2

 

  1. Define : (i) Gels (ii) Brownian movement 2

 

  1. Explain and describe what happens when :             3
  • An electric current is passed through a colloidal solution.
  • FeCl3 is mixed with freshly prepared Fe(OH)3
  • Light is passed through a colloidal solution.

 

  1. Differentiate between chemisorption & physisorptin.             3

 

  1. Explain Langmuir adsorption isotherm. 2

 

  1. Account for the following: 2

(i) A delta is formed at a point where river enters the sea.

(ii) As2S3 sol posses negative charge.

 

  1. Explain activity and selectivity of a catalyst.             2

 

  1. Explain Bredig’s Arc method.                                                                                                                  2

 

  1. Give an example of water in oil type of emulsion. What type of emulsifier can be used for such emulsions?                                                                                                                                                 2

 

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