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CBSE Important Questions

CBSE Guess > Papers > Important Questions > Class IX > 2009 > Science > Science By : Mr M. p. Keshri

CBSE CLASS I X

Structure Of The Atoms (Solved)

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Syllabus :


Charged particles in matter; The structure of an atom; Distribution of electrons in shells; Valence electrons and valency; Atomic number and mass number; Isotopes.

 

Q. 1. How can you say that matter is electrical in nature ?


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Q. 2. Write about a discharge tube.


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Q. 3. State the cathode rays. How are they produced ?


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Q. 4. Give important properties of cathode rays.


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Q. 5. Write the observation made, while conducting a discharge experiments, which showed that :

(i) Cathode rays travel in straight line.

(ii) Cathode rays are made up of material particles having mass and kinetic energy.

(iii) Cathode rays are negatively charged.


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Q. 6. How will you explain the flow of current in a cathode ray experiment, knowing that gases are bad conductors of electricity ?


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Q. 7. A part of the glass glow in the discharge tube experiment. Why ? Name the scientist who performed this experiment for the first time.


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Q. 8. What are X-rays ?


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Q. 9. State the properties of X-rays.


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Q. 10. State the use of X-rays.


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Q. 11. Explain how X-rays are used to locate craks in fractured bones.


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Q. 12. Give one use of X-rays giving the property which makes this use possible.


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Q. 13. What is the mass and charge of an electron ?


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Q. 14.Draw a diagram to show the presence of charge on cathode rays in the discharge tube and label it.


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Q. 15. “Electrons are common constituents of all matter”. Comment.


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Q. 16. How can you say that cathode rays are negatively charged particles ?


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Q. 17. Experimentally show that cathode rays travel in straight line.


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Q. 18. What is phosphorescence ?


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Q. 19. Describe the different stages observed when a discharge tube is connected to a high voltage source and the pressure of the air in it is reduced gradually.


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Q. 20. What happens when the cathode rays are passed through an electric field between two parallel plates ? What do you conclude with this experiment ?


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Q. 21. State anode or positive rays. How are they produced ?


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Q. 22.  State the important properties of anode rays.


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Q. 23. State the observation that led to the conclusion that the nature of the anode rays depend upon the gas used in the cathode rays tube.


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Q. 24. What can you say about the mass of the particles of anode rays ?


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Q. 25. Explain how electricity is conducted through gases at very low pressures.


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Q. 26. What is proton ? State its characteristics.


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Q. 27. Differentiate between cathode rays and positive rays.


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Q. 28. “All substances contain protons in addition to electrons”. Comment.


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Q. 29. State the nature of charge on :

(i) X-rays

(ii) Cathode rays

(iii) Gamma rays

(iv) Anode rays.


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Q. 30. State the differences in the discharge tube used to study cathode rays and the anode rays.


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Q. 31. Name the fundamental particles discovered by

(i) Thomson

(ii) Goldstein

(iii) Chadwick.


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Q. 32. ‘The mass and charge on positive rays change with change in nature of the gas in the discharge tube’. Give reason for this.  


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Q. 33. State the significance of nature of protons found in the different elements.


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Q. 34. What are canal rays ?


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Q. 35. If an atom contains one electron and one proton, will it carry any charge or not ?


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Paper By Mr. M. P. Keshari [ For Further Enquiry 09434150289]