Chemical Reactions and Equations

CHEMICAL REACTIONS AND EQUATIONS

Very Short Answer Types Question (SAQ) 1. What is meant by the skeletal equation? Answer : The equation where the...

SHORT ANSWER TYPE QUESTIONS (SAQ)

1. On heating blue coloured powder of copper (II) nitrate in a boiling tube, black copper oxide, O2 and a brown gas X is...

2. Answer the following questions: (i) Write the essential condition for the following reaction to take place: 2AgBr...

3. Identify the type of each of the following reactions. Also write the balanced chemical equation involved. (i) The rea...

4."We need to balance a skeletal chemical equation." Give reason to justify the statement. Answer : Skeletal chem...

5. Listfour observations that help us to determine whether a chemical reaction has taken place. Answer : The observ...

6. Answer the following questions: (i) A shiny brown-coloured element 'X' on heating in air becomes black in colour. Nam...

8. Decomposition reactions require energy either in the form of heat or light or electricity for beaking down the reacta...

9. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricit...

10. Decomposition by electricity: It is also known as electrolysis. Electrolysis of lead bromide: Answer : PbBr2 →...

11. What does one mean by exothermic and endothermic reactions? Give examples. Answer : Exothermic reactions releas...

12. Write the chemical equation of the reaction in which the following changes have taken place with an example of each...

13. What do you mean by a precipitation reaction? Explain by giving examples. Answer : A precipitation reaction hap...

14. When a solution of potassium iodide is added to a solution of lead nitrate in a test tube, a reaction takes place....

15. During the reaction of some metals with dilute hydrochloric acid, the following observations were made by a student....

16. Define the term decomposition reaction. Give one example of each of thermal decomposition and electrolytic decomposi...

16. Electrolytic decomposition or electrolysis: Decomposition takes place by electricity. Example, electrolysis of alumi...

17. A white salt on heating decomposes to give brown fumes and a residue is left behind. (i) Name the salt. (ii) Write...

18. assed over the hot black substance so formed, it regains its original colour. Based on the above information, aWhen...

19. Answer the following questions: (i) Why is respiration considered as an exothermic reaction? (ii) Define the terms o...

20. The following diagram displays a chemical reaction. Observe carefully and answer the following questions: (i) Identi...

21. Answer the following questions: (i) Classify the following reactions into different types. (a) AgNO3(aq) + NaCl → A...

22. Identify the type of reactions taking place in each of the following cases and write the balanced equation for the r...

23. What is observed when carbon dioxide gas is passed through lime water. (i) For a short duration (ii) For a long d...

24. 2 g of ferrous sulphate crystals are heated in a dry boiling tube. (i) List any two observations. (ii) Name the type...

25. State the type of chemical reactions and chemical equations that take place in the following: (i) Magnesium wire is...

26. A sample of water weed was placed in water and exposed to sunlight. Bubbles of gas are seen on the surface of the le...

27. State the reason for the following: (i) Potato chips manufacturers fill the packet of chips with nitrogen gas. (ii)...

28. Barium chloride solution and sodium sulphate solution are mixed together? What is the colour of precipitate? Write t...

29. Why is it necessary to balance a chemical equation? Answer : 1. We balance a chemical equation because of the L...

30. What is the method of balancing chemical equations? Answer : For balancing simple chemical equations, we use th...

31. What are the different ways that can make chemical equations more informative. Answer : Chemical equations can...

32. What is the role of a catalyst in a chemical reaction? Answer : A catalyst is a substance that speeds up a rea...

33. Write the uses of decomposition reactions. Answer : 1. Metal Extraction : Metal extraction is important for ge...

34. What are the characteristics of chemical reactions? Answer : Characteristics of chemical reactions are as follo...

35. What is a precipitation reaction? Give an example. Answer : A precipitation reaction happens when two soluble s...

36. What is a redox reaction? Answer : A redox (reduction-oxidation) reaction is a type of chemical reaction that in...

37. Give balanced equations, wherever possible, or where this is not possible, explain the following by means of example...

38. What is a balanced chemical equation? Answer : A balanced chemical equation is when the number of atoms in the...

39. Write the chemical equation involved in the following chemical reactions: (i) White washing (ii) Black and White pho...

40. 2 g of silver chloride is taken in a china dish and the china dish is placed in sunlight for sometime. What will be...

41. Solutions of ferrous sulphate, zinc sulphate, copper sulphate and aluminium sulphate were separately taken in four t...

42. (i) Name two metals which do not corrode easily. (ii) Corrosion of some metals is an advantage, given an example to...

43. Can rancidity retard by storing foods away from the light? Answer : This concept is known as rancidity. Rancid...

44. In the equations given below, state giving reasons, for whether substances have been oxidized or reduced. (i) PbO +...

45. Answer the following questions: (i) While studying the combination reaction on adding water to quicklime, name the p...

46. You want to study a decomposition reaction by taking ferrous sulphate crystals in a boiling tube. List two precautio...

47. Why does the colour of copper sulphate solution change when an iron nail is dipped in it? Write two observation and...

48. Answer the following questions: (i) What is the colour of ferrous sulphate solution? (ii) What happens when ferrou...

49. While performing an experiment a student observes that when he heat some green crystals in a boiling tube, the colou...

50. Answer the following questions: (i) When magnesium ribbon burns in air or oxygen, a product is formed. State the typ...

LONG ANSWER TYPE QUESTIONS (LAQ)

1. State one characteristic each of the chemical reaction which takes place when: (i) Dilute hydrochloric acid is added...

2. On heating blue coloured powder of copper (II) nitrate in a X is formed. (i) Identify the type of reaction and the ga...

3. On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite, white precipitate is obtained...

4. Answer the following questions: (i) Solid calcium oxide was taken in a container and water is added slowly to it. (a)...

5. Tina finds a paper covered with a white substance in a chemistry lab. She keeps the paper near the window of the lab...

6. Answer the following questions: i) Define corrosion. (II) What is corrosion of iron called? (iii) How will you recog...

7. Answer the following questions: (i) Explain two ways by which food industries prevent rancidity. (ii) Discuss the...

8. Identify the type of chemical reaction in the following statements and define each of them. (i) Digestion of food in...

9. Define a chemical reaction. State four observations which help us to determine that a chemical reaction has taken pla...

10. Answer the following questions: (i) Define a balanced chemical equation. Why should an equation be balanced? (ii...

NCERT SOLUTION

Page No. 6 1. Why should a magnesium ribbon be cleaned before burning in air?...

Page No. 10 1. A solution of a substance, ‘X,’ is used for whitewashing. (i) Na...

Page No. 13 1. Why does the colour of copper sulphate solution change when an ir...

1. Which of the statements about the reaction below are incorrect? 2PbO(s) + C(s) → 2Pb(s) + CO₂(g)...

2. Fe₂O₃ + 2Al → Al₂O₃ + 2Fe The above reaction is an example of a - (a) Combination reaction...

3. What happens when dilute hydrochloric acid is added to iron filings? Tick the correct answer:...

4. What is a balanced chemical equation? Why should chemical equations be balanced? Answer: Balanced Chem...

5. Translate the following statements into chemical equations and then balance them. (a) Hydrogen gas combines...

6. Balance the following chemical equations: (a) HNO₃ + Ca(OH)₂ → Ca(NO₃)₂ + H₂O Balanced Chemical Equatio...

7. Write the balanced chemical equations for the following reactions: (a) Calcium hydroxide + Carbon dioxide →...

8. Write the balanced chemical equation for the following and identify the type of reaction in each case. (a)...

9. What does one mean by exothermic and endothermic reactions? Give examples. Answer: Exothermic Reaction...

10. Why is respiration considered an exothermic reaction? Explain. Answer: Respiration is considered an e...

11. Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactio...

12. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light, or ele...

13. What is the difference between displacement and double displacement reactions? Write equations for these reacti...

14. In the refining of silver, the recovery of silver from silver nitrate solution involves displacement by copper...

15. What do you mean by a precipitation reaction? Explain by giving examples. Answer: Precipitation React...

16. Explain the following in terms of gain or loss of oxygen with two examples each: (a) Oxidation (b) Redu...

17. A shiny brown-colored element X on heating in air becomes black in color. Name the element X and the black-colo...

18. Why do we apply paint on iron articles? Answer: We apply paint on iron articles to prevent them from...

19. Oil and fat containing food items are flushed with nitrogen. Why? Answer: Oil and fat-containing food...

20. Explain the following terms with one example each: (a) Corrosion (b) Rancidity Answer: (a) Co...