Month: April 2022

class 9 science chapter 5 important questions

  1. Name the cell organelles which is called suicidal bag of the cell.
  2. Which cell organelles are termed as power house of cell?
  3. Name the cell organelles that have double layered enveloped system.
  4. Who proposed the fluid mosaic model?
  5. Who coined the term cell?
  6. Name the scientist who proposed the cell theory and who gave the idea that the cells arise from pre-existing cell.
  7. Give two example of unicellular organism.
  8. Name the longest cell of human body.
  9. Name the membrane that covers the vacuoles.
  10. What will happen when human RBC placed in hypertonic solution?
  11. Name the carrier protein that helps in transport of material across the material.
  12. Where are the genes located?
  13. Name the source of illumination in electron microscope.
  14. Give full form of ATP.
  15. Define cell.

class 9 science chapter 4 important questions

  1. What are cations and anions.
  2. What is Thomson’s model of atom? What is its drawback?
  3. What are isobars? Comment on their physical and chemical properties.
  4. Give any three important characteristics of cathode rays.
  5. Give any two proofs to show that electrons are universal constituent of all atoms.
  6. What was drawback of Ruttherford’s model of atom?
  7. How was electron discovered? Explain briefly.
  8. How was proton discovered? Explain briefly.
  9. Write the important features of Bohr’s model of atom.
  10. How was neutron discovered? Explain briefly.
  11. What are isotopes? Give their important applications.
  12. Write the electronic configuration of potassium atom (Atomic number of potassium=19). What will be its valency?
  13. Write the isotopes of hydrogen and give their names.
  14. What do you think would be the observation if the alpha-particle scattering experiment is carried out using a foil of a metal other than gold?
  15. Which isotope is used in the treatment of cancer?
  16. The atom of an element has 2 electrons in the M-shell. What is its atomic number? Name the element.
  17. On the basis of Thomson’s model of an atom, explain how the atom is neutral as a whole.
  18. What do you understand by ground state and excited state of an atom?
  19. Give at least three proofs to show that electrons are present in all atoms.

most important questions for class 9th chapter 4

  1. Give two examples from everyday life where we use cathode ray tubes.
  2. What are the actual values of charge and mass of the electron?
  3. Define electron.
  4. Name the scientist who showed the existence of protons in atoms?
  5. What are canal rays?
  6. Define proton.
  7. In Rutherford’s scattering experiment, some but very few alpha particles are deflected back. What does it prove?
  8. Why are Bohr’s orbits called stationary states?
  9. What are the symbols used to represent different orbits? Arrange them in order of energy.
  10. What do you mean by ground state, of an atom?
  11. What do you mean by excited state, of an atom?
  12. Who discovered neutron and when?
  13. Define neutron,.
  14. What is the maximum number of electrons that can be present in the outermost shell?
  15. What do you mean by valence electrons?
  16. What is valence shell?
  17. What do you mean by valency, of an element?
  18. What are isotopes? Give one example.
  19. Represent the three isotopes of hydrogen and give their names.

class 9th, science chapter 3, important questions

  1. What are isotopes? Give two examples.
  2. How is the valency of an atom related to its electronic configuration?
  3. Calculate the atomic number of the element whose atomic nucleus has mass number of 23 and neutron number 12.What is the symbol for this element?
  4. Nucleus of an atom has 5 protons and 6 neutrons.What would be the atomic number,the mass number,the number of electrons and the number of valency electrons per atom of this element?
  5. What valency will be shown by an element having atomic number 15?
  6. An element has atomic number 16 .How many electrons will be present in K,L and M energy shells of its atom? What will its electro-valency be?
  7. What are valence electrons? Write the number of Valency electrons present in the elements: carbon,sodium and phosphorus.
  8. Draw the electronic structure of sodium and calcium with atomic number 11 and 20 respectively.
  9. Give four differences between cathode rays and canal rays.
  10. Write the main characteristic properties of cathode rays.
  11. Define electron, proton and neutrons.
  12. What is meant by atomic number of an element? Does the atomic number of an element change when its atoms from ions? Give one example each of diatomic and triatomic molecules.
  13. An element M has atomic mass 24 and atomic number 12. How many neutrons does its atom contain? How many electrons will be present in K,L and M energy shells of its atoms ?
  14. An element has atomic number 17. How many electrons will be present in the K,L and M energy shells of the atom?What will its electro-valency be?
  15. Elements A, B, C and D have atomic numbers 11,8,1 and 17 respectively.Give the chemical formulae of the compounds formed between (i) A and D (ii) B and C.
  16. Which fundamental particle is equal in number in Mg2+ and AL3+ ions ?An atom has electronic configuration of 2,8,7

most important questions, class 9th science

  1. Name the element which does not contain any neutron.
  2. Name two elements which have the same atomic number.
  3. An atom of an element is represented as 16/8 A. What is its atomic number and mass number? Also name the element.
  4. An atomof an element has 19 protons, 19 electrons and 20 neutrons.The atomic mass of the element is……….
  5. What is the maximum capacity of outermost shell of an atom?
  6. Name an element which has two valence electrons but is a noble gas.
  7. Which electrons determine the chemical properties of an element?
  8. An element has 8 electrons in its valence shell. What is its general name?
  9. Why isotopes have different mass numbers?
  10. Why do isotopes of an element have different physical properties ?An isotope of lead has a mass number 211 and atomic number 82 (211/82Pb).During radioactive disintegration,gets converted into an element whose mass number remains the same but atomic number increases by 1.Will the end product be an isobar or not ?
  11. What are isotopes?
  12. Write the value of charge on electron.
  13. Define mass number.
  14. Define valency.
  15. Explain the electrical nature of matter.
  16. What are cathode rays and positive rays?
  17. What is the nucleus of an atom?
  18. Define the term mass number giving an example.