Question

19. Which gas is produced on burning a natural gas (CH)?
20. Why does an aqueous solution of an acid conduct electricity?
21. Which is the hardest allotrope of carbon?
22. Mention any two uses of concave mirror
23. What is called an eco-system?
24. Define the unit of electric current.
SECTION - B
Answer the following 40-50 words: (2 mark each) (Any 9)
18
25. Give any two uses of bleaching powder.
26. Write chemical equations for the formation of sodium chloride.
27. Where do plants get each of the raw materials required for photosynthesis?
28. What are the components of the transport system in human being?
29. Draw schematic diagram of transport and exchange of oxygen and carbon
dioxide in human
30. What is the difference between reflex action and walking?
31. A convex mirror used for rear-view an byke has a radius of curvature 3.0 m. If
a bus is located from this mirror is at 5.0 m. Find position of the image.
32. Speed of light in vacuum is 3 x 10 m/s. Find the speed of light in glass slab
having refractive index 1.5.
33. Mention the factors upon which the resistance of metallic conductor depends.
34. What are the disadvantages of fossil fuel?
35. Mention four important points about modern periodic table.
36. What is the importance of DNA copying in reproduction?
SECTION -C
Answer the following 60-80 words: (3 mark each) (Any 6)
18
37. Explain importance of pH in our digestion system,
38. Give uses of baking soda,
Science

Answer 1

Hydrocarbon fuels like methane (CH4) burn in the presence of oxygen to produce carbon dioxide and water. This process of combustion releases energy. When energy is released during the course of a chemical reaction, it is said to be an EXOTHERMIC reaction. The combustion of of methane gas releases 50.1 kJ/g.

whole chapter or what?

Arey nhi

Pura book ka sara question ek sath puch lo na (-_-メ)