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Question
What is meant by ‘surface activity’?
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Solution
The surface activity of a substance is the property by virtue of which it can spread on a surface. For example, soapy water easily spreads on any kind of surface and thus is used for cleaning purposes.
RELATED QUESTIONS
Both soap and detergent are some type of salts. What is the difference between them?
Why do soaps not form lather in hard water?
In the neighbourhood of your school, hard water required for an experiment is not available. Select from the following group of salts available in your school, a group each member of which, if dissolved in distilled water, will make it hard:
(a) Sodium chloride, calcium chloride
(b) Potassium chloride, sodium chloride
(c) Sodium chloride, magnesium chloride
(d) Calcium chloride, magnesium chloride
Would you be able to check if water is hard by using a detergent?
People use a variety of methods to wash clothes. Usually after adding the soap, they ‘beat’ the clothes on a stone, or beat it with a paddle, scrub with a brush or the mixture is agitated in a washing machine. Why is agitation necessary to get clean clothes?
Distinguish between esterfication and saponification reaction with the help of the chemical equations for each.
State one use of esterfication process.
Fill in the following blank with suitable word:
The sodium salt of a long chain fatty acid is called .............
A student takes 4 mL of distilled water in each of four test tubes I, II, III and IV, and then dissolves an equal amount of four different salts namely NaCl in I, CaCl2 in II, MgCl2 in III and KCl in IV. He then adds 8 drops of the given soap solution to each test tube and shakes the contents of the test tube 10 times. In which test tubes will enough lather (foam) be formed ?
(A) I and II
(B) II and III
(C) I and IV
(D) III and IV
How does soap clean clothes?
