question_answer

  A group of students took an old shoe box and covered it with a black paper from all sides. They fixed a source of light (a torch) at one end of the box by making a hole in it and made another hole on the other side to view the light. They placed a milk sample contained in a beaker/tumbler in the box as shown in the figure. They were amazed to see that milk taken in the tumbler was illuminated. They tried the same activity by taking a salt solution but found that light simply passed through it? (i) Explain why the milk sample was illuminated. Name the phenomenon involved. (ii) Same results were not observed with a salt solution. Explain. (iii) Can you suggest two more solutions which would show the same effect as shown by the milk solution?

Answer:

                  Part .4        Part B is not heated so the reaction will be as such In part A,  gas is produced, which is identified by its characteristic smell of rotten egg.                                                                (1+1) In part B,  gas is produced. Hydrogen gas is tested by bringing a burning match stick near the mouth of the test tube. It burns with a pop sound and water is formed.              (1+1)