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Chapter Revision Structure of Atom Class 9 1.The nucleons are I. Protons and electrons II. Neutrons and electrons III. Protons and neutrons IV. None of these 2. The isotope deuterium of hydrogen has I. No neutrons and one proton II. One neutrons and two protons III. One electron and two neutron IV. One proton and one neutron 3. The electrons present in the outermost shell are called I. Valency electrons II. Octate electrons III. Duplet electrons IV. Valence electrons 4. An alpha particle contains I. 4 positive charge and 2 mass unit II. 2 positive charge and 4 mass unit III. 2 positive charge and 2 mass unit IV. 4 positive charge and 4 mass unit 5. The atomic number of sodium is 11 and its mass number is 23. It has I. 11 neutrons and 12 protons II. 12 protons and 11 electrons III. 11 electrons and 12 neutrons IV. 12 electrons and 11 neutrons 6. The electronic configuration of chlorine is I. 2,7 II. 2,8,8,7 III. 2,8,7 IV. 2,7,8 7. The isotope used to remove the brain tumours...

  Important question answer (Chapter Revision)   Q1. A man climbs a slope and another walks the same distance on a level road. Who does more work and why ? Answer: The man who walk on a level road does no work as he is walking at right angle to the direction of gravitational force. Hence the man climbs a slope is doing more work. Q2. State the CGS and SI units of work. Answer : CGS unit of work is erg or gcm2s2 S.I. unit of work is joule or kgm2s2 1 J = 107 ergs or 1 erg = 10-7 g Q3. What is horsepower ? What is its magnitude in SI unit ? Answer : Horse power is unit of power used in engineering 1 H.P = 746 w.  Q4. Prove mathematically the law of conservation of energy. Answer : Law of conservation of energy : “Energy can neither be created nor destroyed. Though it can be transformed from one form to other.” At A Consider a body of mass m at A at a height h above the ground level. P.E. = mgh K.E. = 0 at rest. P.E. + K.E. = mgh + O = mgh …………….. (i) Let it fall from A ...

  Important Question Answer (Chapter Revision); Ready to Test your knowledge Q1. Why does the electric fan continue to rotate for sometime after the current is switched off.?  Ans. The fan continues to rotate due to inertia of motion, until the friction in bearings and that of air brings it to rest.  Q2. Is a train moving on a circular track, an inertial frame of reference.?  Ans. No Q3. A trolley of mass 300kg carrying a sand bag of 25kg is moving at a uniform speed of 27km/h on a smooth track. After a while, sand begins to leak out of a hole on the trolleys floor at a rate of 0.05kg/s. What is the speed of the trolley after the entire sand bag is empty.?  Ans. As the trolley is moving uniformly on a smooth track, no external forces acts on the trolley bag system. Hence its speed will remain 27km/h even after the bag become empty through leakage of sand.  Q4. A Bob of mass 0.1kg hung from the ceiling of a room by a string 2m long is set into oscillation. T...