CHAPTER -1 CHEMICAL REACTIONS
Fill in the Blanks
1. The addition of oxygen to a substance is called …………. whereas removal of oxygen is called …………. .
2. The addition of hydrogen to a substance is called …………. whereas removal of hydrogen is called …………. .
3. Precipitation reactions produce insoluble …………. .
4. Reactions in which energy is given out are known as …………. .
5. Reaction in which an element displaces another element from its compound is called …………. .
6. Two antioxidants which are usually added to fat and oil containing foods to prevent rancidity, are …………., …………. .
7 …………. is the process in which metals are eaten up gradually by the action of air, moisture or a chemical on
their surface.
8. 2 FeSO4 → Fe2O3 + SO2 + ………….
9. Na2SO4 + BaCl2 → …………. + 2NaCl
10. Complete the missing components/variables given as x and y in the following reactions:
(a) Pb (NO3)2 (aq) + 2KI (aq) → Pbl2 (x) + 2KNO3 (y)
(b) Cu (s) + 2AgNO3 (aq) → Cu (NO3)2 (aq) + x (s)
Answers
1. oxidation, reduction
2. reduction, oxidation
3. salts
4. exothermic reactions
5. displacement reaction
6. BHA and BHT
7. Corrosion
8. SO3
9. BaSO4
10. (a) x → (s); y → (aq);
(b) x → 2Ag
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1.Which reaction is an example of a combination reaction and a decomposition reaction?
(a) both the reactions are examples of combination reaction
(b) both the reactions are examples of a decomposition reaction
(c) reaction P is an example of a combination reaction while reaction Q is an example of a decomposition reaction
(d) P is an example of a decomposition reaction while reaction Q is an example of a combination reaction
2. From the following which one is the example of chemical reaction?
(a) Grapes get fermented
(b) Breakdown of food
(c) Formation of curd
(d) All of the above
3. A student adds lead and silver to two different test tubes containing an equal amount of copper sulphate solution. The student observes that the color of the solution in the test tube with lead changes. What explains the change in the colour of the solution?
(a) A displacement reaction takes place as lead replaces copper from the solution.
(b) A combination reaction takes place as lead combines with sulphate in the solution.
(c) decomposition reaction takes place as copper dissociates from sulphate in the solution.
(d) A double displacement reaction takes place as copper dissociates from sulphate and lead combines with sulphate in the solution.
4. Which of the reactions is used in black and white photography?
(a) Combination Reaction
(b) Decomposition Reaction
(c) Displacement reaction
(d) Oxidation reaction
5. What happens when lead nitrate reacts with potassium iodide?
(a) They will not react
(b) Large amount of hydrogen release
(c) Yellow ppt of lead iodide and potassium nitrate will be produced
(d) Evolution of gas will occur
6.What happens when lead nitrate reacts with potassium iodide?
(a) They will not react
(b) Large amount of hydrogen release
(c) Yellow ppt of lead iodide and potassium nitrate will be produced
(d) Evolution of gas will occur
7. What can be inferred from the chemical equation?
(a) silver nitrate and potassium undergo a decomposition reaction to form silver chloride and potassium nitrate
(b) silver nitrate and potassium undergo a displacement reaction to form silver chloride and potassium nitrate
(c) silver nitrate and potassium undergo a combination reaction to form silver chloride and potassium nitrate
(d) silver nitrate and potassium undergo double displacement reaction to form silver chloride and potassium nitrate
8. Which of the following does show an oxidation reaction?
(a) Gain of oxygen
(b) Loss of oxygen
(c) Gain of hydrogen
(d) None of the above
9. Which of the following gases can be used for storage
(a) Carbon dioxide or Oxygen
(b) Nitrogen or Oxygen
(c) Carbon dioxide or Helium
(d) Helium or Nitrogen
10.Name the products formed when iron filings are heated with dilute hydrochloric acid
(a) Fe (III) chloride and water
(b) Fe (II) chloride and water
(c) Fe (II) chloride and hydrogen gas
(d) none
11.Which of the following is an endothermic process?
(a) Dilution of sulphuric acid
(b) Sublimation of dry ice
(c) Condensation of water vapours
(d) Respiration in human being
12.