1. Q81 What are pneumatic bones?
  2. Q82 What are simple epithelial tissues?
  3. Q83 What is an electronic configuration of an element?
  4. Q84 List the general characteristics of pteridophytes.
  5. Q85 Bryophytes are used in pots. Why?
  6. Q86 Why was the system of classification of elements into triads not found suitable?
  7. Q87 What will happen if we kill all the organisms in one trophic level?
  8. Q88 A 10 mm long pin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is:
  9. Q89 The metal salt A is blue in color. When salt A is heated strongly over a burner, then a substance B present in it is eliminated and a white powder C is left behind. When a few drops of a liquid D are added to powder C it becomes blue again. (a) Identify A, B, C, D
  10. Q90 Write a chemical equation of the reaction stating its type. The white compound is lead nitrate and brown fumes are of nitrogen dioxide and yellow residue is lead oxide.