Sample Paper 1 for Class XII




  1. What are hypotonic and hypertonic solutions? 4% sucrose solution is isotonic with 3% solution of an unknown organic substance. Calculate the molecular mass of the unknown solute.                                                        3


  1. Define vapour pressure. How much urea (molar mass 60 g/mol) should be dissolved in 50 g of water so that its vapour pressure at room temperature is reduced by 25%.                                                                                3


  1. With the help of a suitable diagram show that the lowering of V.P. of a solution containing non volatile solute causes a lowering of freezing point of the solvent.                                                                                            2


  1. Differentiate between ideal and non ideal solutions taking suitable example.                                                   2


  1. State Henry’s law. State its two applications.                                                                                                    2


  1. When is the value of Van’t Hoff factor greater than one and less than one? What is the Van’t Hoff factor for 0.1 M BaCl2 which is 90% dissociated?                                                                                                                  2


  1. Give reasons:                                                                                                                                                    2

(a) The relative lowering of vapour pressure of 0.1 M NaCl and 0.1 M urea solution at the same temperature is not found to be same.

(b) Aquatic life is more comfortable in winters than in summers.


  1. 2g of benzoic acid (C6H5COOH) dissolved in 25 g of benzene shows a depression in freezing point equals to 1.62 K. Molal depression constant for benzene is 4.9 K Kg/mol. What is the percentage association of acid if it forms dimer in solution?                                                                                                                                    3


  1. What is the effect of temperature on molarity and molality of a solution?                                                         1



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