Question

In three test tubes À, B, C, three different liquids namely,distilled water, underground water and distilled water in which a pinch of calcium sulphate is dissolved,respectively are Taken.equal amount of soap solution is added to each test tube and thé contents are shaken.in which test tube Will thé length of thé foam(lather) be longest ? Justify your answer.

Answer 1

B . No scum in B.........

Answer 2

The test tube with the length of the foam (lather) longest is test tube A.

Explanation

- Distilled water in test tube A is soft water and forms lather easily

- But underground water & water containing calcium sulfate contain calcium & magnesium salts and so are hard water.

- They react with soap solution and forms scum due to calcium & magnesium salts with little lather.

- Test tube B and C forms little lather and some scum.

So the test A with distilled water has the longest foam.

Hope this helps.