CBSE Important Questions

Science Class X

Index

Q. 1. Answer the following questions:

  1. Metal that is found in liquid state at room temperature.
  2. The best conductor of heat.
  3. The metal showing least conductivity of heat.
  4. The best conductor of electricity.
  5. The metal having maximum résistance in the conduction of electricity.
  6. Metals, which are cut with a knife at room temperature.
  7. The most ductile metal.
  8. The most malleable metal.

Q. 2. Explain why;

  1. Zinc is coated over iron sheets?
  2. Copper is used to prepare electrical wires.
  3. Sodium is not found in free state in nature.

Q. 3. On the basis of electronic structure, define metals and non-metals giving suitable example.

Q. 4.Write the equation for the reaction, which takes place when sodium oxide reacts with water. How will this solution behave towards phenolphthalein and red litmus paper?

Q. 5.You are given samples of three metals: sodium, magnesium and copper. Suggest any two activities to arrange them in order of their decreasing reactivity.

Q. 6.Why some metals is more reactive and some are less reactive? Explain.

Q. 7.What will happen if a strip of copper is kept immersed in a solution of silver nitrate (AgNO3)?

Q. 8.An iron knife kept dipped in a blue copper sulphate solution turns the blue solution light green. Why?

Q. 9. A, B and C are three elements which undergo chemical changes according to the following equations:
A2O3 + 2 BB2O3 + 2A
2CSO4 +2 BB2(SO4)3 + 3C
3CO +2A A2O3 +3C

Q. 10. Write the name of the most reactive and the least reactive elements.

Q. 11. What is meant by the term metallurgy? Name its three steps.

Q. 12. What is meant by ore concentration? Name any two common processes of ore concentration.

Q. 13. Write short note on the following methods for the concentration of ores:
Forth floatation method and leaching process

Q. 14. What is the difference between roasting and calcinations? Which one of tow is used for sulphide ores?

Q. 15. How reduction of metal oxides is carried to convert them into metals? How reactivity series is helpful in carrying the reduction of the metals?

Q. 16. Explain how the following metals are obtained from their compounds by the reduction process:

  1. Metal x, which is low in the reactivity series.
  2. Metal y, which is in middle the reactivity series.
  3. Metal z, which is high up in the reactivity series.

Q. 17. Describe the methods used for the refining of impure metals.

Q. 18. Give the differences between

  1. Liquation and hydraulic washing.
  2. Electrolytic reduction and reduction with carbon.

Q. 19. Describe the extraction of (a) Al and (b) Fe, giving the following details.(i). Ore, (ii) Concentration, (iii) Conversion of ore into oxide of metal, (iv) Refining of metal.

Q. 20.Metal M occurs in the earth’s crust as its oxide M2O3. An alloy of this metal is used in making aircraft. Name the ore of this metal containing M2O3. Explain the steps taken to obtain this metal in a pure form from this ore and draw a labeled diagram for the process.

Q. 21.Most of the iron ore that we use today is iron oxide mixed with silicon dioxide. How is iron oxide mixed with silicon dioxide? How is iron obtained from it? Write the chemical reactions involved. Name the furnace in which this chemical process takes place. Draw a labeled diagram of the furnace.

Q. 22.Why is limestone added to the blast furnace in the extraction of iron from haematite?

Q. 23.State the difference between (i) iron and steel and (ii) stainless steel and steel.

Q. 24.Describe the methods used for obtaining metals of very high purity.

Q. 25.An ore gives CO2 on treatment with dilute acid. Identify the ore and name the process that should be used to concentrate this ore. Outline two steps that should be taken to convert such a concentrated ore into free metal.

Q. 26. A woman stored her utensils made up of copper in a room. After some months she found that the copper utensils had lost their luster due to formation of greenish layer on them. State two reasons for this change.

Q. 27. M is an element, which is one amongst copper, zinc aluminum and iron. It shows the following properties;

  1. a. One of its ores is rich in M2O3.
  2. M2O3is not affected by water.
  3. It forms two chlorides MCl2 and MCl3.

Name the element and give justification in support of your answer.

Q. 28. Element E has electronic configuration 2,8,3 and occurs in earth crust as its oxide E2O3. It is more reactive than Zinc. Answer the following:

  1. What is the name of element?
  2. Name the ore from which element E is extracted.
  3. Write two important uses of E.

Q. 29. Explain why

  1. Aluminum cannot be extracted by reduction of its ores by carbon.
  2. Does aluminium not react with cold water under ordinary conditions?
  3. Concentrated sodium hydroxide solution cannot be stored in aluminium containers.

Q. 30 . What is rusting of iron? Write any two common methods to prevent rusting.

Q. 31. Compare the properties of metals and non-metals.

Q. 32. Write the reactions of the following on non-metals:
O2 (ii) Acids (iii) Cl2 (iv) H2

Q. 33 . Why are metals reducing agents whereas non-metals are oxidizing agents?

Q. 34. Write the methods of preparation of Hydrogen.

Q. 35. How H2 is prepared at large scale?

Q. 36. Describe the preparation of H2 by Bosch Process.

Q. 37. Write the reactions of NH3 with metal ions.

Q. 38. Draw a labeled diagram for Frasch process of extraction of sulphur from sulphur beds:

  1. What is the function of super heated water in this process?
  2. Why is sulphur pushed out through the middle pipe?

Q. 39. What happens when sulphur reacts with (i) Con.H2SO4,(ii) Con.HNO3? Write the chemical equations of the reactions.

Q. 40. A non –metal belonging to the sixth group of the periodic table is mined by a special technique based on the fact that is has a comparatively low m.p. Identify the non-metal and explain the process of its extraction.

Q. 41. What is vulcanization of rubber? Name the substance used for this purpose.

Q. 42. Write the use of H2SO4.

Q. 43. Give reasons:

  1. Metals replace H2 from dil. Acids whereas non-metals do not.
  2. Carbonate and sulphides ores are usually converted into oxides.

Q. 44. Ammoniais manufactured form N2 and H2 by Haber process. The process is carried out at 200-300 atm and 723-773K.

  1. Give one reason for not using a very high pressure.
  2. Give one reason for not using a lower temperature.
  3. How could ammonia be separated form other two gases?

Q. 45.Define allotropy. Name an allotrope of sulphur, which is stable at room temperature.

Q. 46.What would you observe when sulphur dioxide is passed through (i) lime water, (ii) acidified potassium dichromate solution.

Q. 47. In the contact process for the manufacture of sulphuric acid.

  1. Name the catalyst.
  2. Name the substance in which SO3 is dissolved.
  3. Name the substance, which is diluted with water.

Paper By A.K.Nagar
Chandrima Toppers Institute
11-A, G &JU, Maharaja Aggrasain Apartments,
Pitam Pura, New Delhi - 110088, Phone-27343024, 27345104
Mobile – 9868070676, 9990673331, 9990673332

Submitted By : Mr. A.K.Nagar
Index