Section A Answer the following question Q. no. 1 to 13 (within the limit of 10 to 20 words) as directed: (1 mark each) 1. What do you mean by free fall? 2. What do you mean by acceleration Q due to gravity? 3. What are the differences between the mass of an object and its weight? 4. What do you mean by buoyancy? 5. Why does an object float or sink when placed on the surface of water? 6. Define 1 J of work. 7. What is the kinetic energy of an object? 8. How does the sound produced by a vibrating object in a medium reach your ear? 9. What do we get from cereals, pulses, fruits and vegetables? 10. How does the atmosphere act as a blanket? 11. What causes winds? 12. How are clouds formed? 13. List any three human activities that you think would lead to air pollution. Section B Answer the following question Q. no. 14 to 27 (within the limit of 40 to 50 words) directed (2 marks each). 14. Relative density of sil...