question_answer

Iron fillings and sulphur were mixed together and divided into two parts, 'A' and 'B'. Part 'A' was heated strongly, while part 'B' was not. When dil. Hydrochloric acid was added to both the parts, evolution of gas was seen in both cases. How will you identify the gases evolved? OR During an experiment, the students were asked to prepare a 20% (m/m) solution of sugar in water. Meena dissolved 20 g of sugar in 100 g of water, while Rita dissolved 20 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 per cent of the two solutions.    

Answer:

Part A             (1) Part B Mixture of iron filings and sulphur on adding Sulphur remains unreacted.                          (1) Identification  gas formed has a foul smell and on passing through lead acetate solution, it turns the solution black.           (2) Hydrogen gas burns with a pop sound. OR (i) Number as mass per cent         (1) (ii) Meena prepared solution of concentration.                                         (2)                                           (2) Rita prepared solution of concentration. So, the solution prepared by Rita has higher mass percentage than that of prepared by Meena.                                                (2)