Q26 of 61 Page 1

In order to study saponification reaction we first prepare 20% solution of sodium hydroxide. If we record the temperature of this solution just after adding sodium hydroxide flakes to water and also test its nature using litmus, it may be concluded that the process of making this solution is to

The correct answer is: option (a)

When Sodium Hydroxide is added to water, there is release of large amount of heat. So, the reaction is exothermic and the solution is alkaline.

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24

The position of three elements A, B and C in the Periodic Table are shown below:





















































Group



I



II



III



IV



V



VI



VII



Period










1



B









2









A



3








C




Giving reasons, explain the following:


(a) Element A is a non-metal.


(b) Atom of elements C has a larger size than atom of element A.


(c) Elements B has a valency of 1.

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While studying saponification reaction for the preparation of soap, the teacher suggested to a student to add a small quality of common salt to the reaction mixture. The function of common salt in this reaction is to:

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A student has obtained the image of a distant object with a concave mirror to determine its focal length. If he has selected a well illuminated red building as object, which of the following correctly describes the features of the image formed?