Q35 of 55 Page 1

Can we test hard water by using detergent? Write one more method other than using soap to test the hardness of hard water.

No, we can’t test the hard water using detergent because detergent can form lather in both hard as well as soft water.


The other method to test the hardness of hard water is by boiling the soft water. On boiling the water, the insoluble salt’s precipitates will settle down and these can be removed by filtration. The water left will be hard water.


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33

While performing the experiment with raisins to determine the percentage of water absorbed by them, a student made following measurements: 1

Mass of water in the beaker = 40 g


Mass of raisins before soaking = 5 g


Mass of raisins after soaking or 2 hours = 8 g


Mass of water left in the beaker after the experiment = 35 g


The percentage of water absorbed by raisins is:

 34

How will you distinguish between a concave mirror and convex mirror in the Laboratory?

 36

Out of potato, sweet potato, radish and carrot; make pairs of Homologous organs and Analogous organs.

 1

Name the functional group present in each of the following compounds: 1

(i) HCOOH (ii) C2H5CHO