question_answer

  During an experiment the students were asked to prepare a 10% (mass/mass) solution of sugar in water. Ramesh dissolved 10 g of sugar in 100 g of water while Sarika prepared it by dissolving 10 g of sugar in water to make 100 g of the solution. (i) Are the two solutions of the same concentration? (ii) Compare the mass % of the two solutions.

Answer:

                  (i) Physical change Because evaporation of water takes place but no change occurs in the composition of the substance.                     (1) (ii) Physical change It is also involving only movement of air, no change in the composition of air.                                           (1) (iii) Physical as well as chemical change First physical change when kerosene vaporises. After that, burning of kerosene is a chemical change as new products are formed.       (1) (iv) Physical change As there occurs only the dissolution.                                                        (1) (v) Physical change As there is no change in composition. Only the separation of components takes place by the physical phenomenon of centrifugation.                  (1)