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CBSE Guess > Papers > Question Papers > Class X > 2008 >Science > Science Theory

Write the name of the following :
(i) CH3CH2COOH
(ii) CH3CH2Br
(iii) Draw the electron dot structure of ethene (C2H4).

Ans.



(b)

  1. CH3CH2COOH Propanoic Acid
  2. CH3CH2Br Bromo ethane

(c) Electron dot structure of ethene (C2H4 ).

Section B


Q.17. What is the role of saliva in the digestion of food?

Ans. The saliva contains an enzyme called salivary amylase which digests the starch present in food into sugar. Thus, the digestion of starch begins in the mouth.

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Ans. The use of iodised salt is advisable because iodine is required by the thyroid gland to make thyroxine hormone. Iodised salt contains appropriate amount of (potassium iodide). Iodised salt can provide all the iodine needed by thyroid gland to make sufficient thyroxine for our body. So, it helps in preventing goitre.

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Science 2008 Question Papers Class X
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