CBSE Guess > Papers > Question Papers > Class X > 2008 >Science > Science Theory Write the name of the following : Ans. (b)
(c) Electron dot structure of ethene (C2H4 ).
Section B
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. Q.18. Why is the use of iodised salt advisable? 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. Q. 19. Why is ozone layer getting depleted at the higher levels of the atmosphere? Ans. The depletion of ozone layer is due to the use of chemicals called chlorofluorocarbons widely used in refrigeration as coolant.
CBSE 2008 Question Papers Class X
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