Q25 of 58 Page 1

Which of the following sets of materials can be used for conducting a saponification reaction for the preparation of soap?

Soaps are sodium or potassium salts of long fatty acids. They are prepared by the reaction of a long chain fatty acid with either NaOH or KOH. This reaction is known as saponification reaction. Among the given set of materials, a soap can be prepared by the reaction between NaOH and neem oil (long chain fatty acid).

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(a) Draw a ray diagram to show the formation of image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus.

(b) In the above ray diagram mark the object-distance (u) and the image-distance (v) with their proper signs (+ve or -ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the convex lens in this case.


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(a) Write the function of each of the following parts of human eye:

cornea; iris; crystalline lens; ciliary muscles


(b) Millions of people of the developing countries of the world are suffering from corneal blindness. These persons can be cured by replacing the defective cornea with the cornea of a donated eye. A charitable society of your city has organize a campaign in your neighbourhood in order to create awareness about this fact. you are asked to participate in this mission how would you contribute in noble cause?


(i) State the objective of organizing such campaigns.


(ii) List two arguments which you would give to motivate the people to do their eyes after death.


(iii) List two value which are developed in the persons who actively participate and contribute in such programmes.

 26

A student takes four test tubes marked P, Q R and S of 25 mL capacity and fills 10 mL of distilled water in each. He dissolves one spoon full of four different salts in each as-KCl in P, NaCl in Q CaCI2 in Rand MgCI2 in S. He then adds about 2 mL of a sample of soap solution to each of the above test tubes. On shaking the contents of each of the test tubes, he is likely to observe a good amount of lather (foam) in the test tubes marked:

 27

Consider the following comments about saponification reactions:

(I) Heat is evolved in these reaction.


(II) For quick precipitation of soap sodium chloride is added to the reaction mixture.


(III) Saponification reactions are special kind of neutralization reactions.


(IV) Soaps are basic salts of long chain fatty acids.


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