S CHAND CHEMISTRY

ery Short Answer Type Questions I. 2. 3. 4. 5. 6. 7. S. 9. 10. 11. Why is respiration considered an exothermic ? On what basis is a chemical equation balanced ? What happens chemically when quicklime is added to water filled in a bucket ? Why should magnesium ribbon be cleaned before burning in air ? State whether the following statement is true or false : A chemical equation can be balanced easily by altering the formula Of a reactant or product. What is wrong with the following chemical equation ? Mg + 0 NIgO Correct and balance it. What does the symbol (aq) represent in a chemical equation ? Why is photosynthesis considered an endothermic reaction ? How will you indicate the following effects in a chemical equation ? (a) A solution made in water (b) Exothermic reaction (c) Endothermic reaction Translate the following statements into chemical equations and then balance the equations • (n) Hydrogen sulphide gas burns in air to give water and sulphur dioxide. (b) Phosphorus burns in oxygen to give phosphorus pentoxide. (c) Carbon disulphide burns in air to give carbon dioxide and sulphur dioxide. (d) Aluminium metal replaces iron from ferric oxide, Fe203, giving aluminium oxide and iron. (e) Barium chloride reacts with zinc sulphate to give zinc chloride and barium sulphate. Write the balanced chemical equations for the following reactions : (n) Calcium hydroxide + Carbon dioxide —i Calcium carbonate + Water (b) Aluminium + Copper chloride —i Aluminium chloride + Copper

 

CHEMICAL REACTIONS AND EQUATIONS 12. Complete and balance the following equations : 19 (n) NaOH + _+ Na2S04 + 13. Correct and balance the following equations : (i) ca + H20 CaOH + H 14. Write comple te balanced equations for the following reactions • (n) Calcium (solid) + Water (liquid) Calcium hydroxide (solution) + Hydrogen (gas) (b) Sulphur dioxide (gas) + Oxygen (gas) —i Sulphur trioxide (gas) 15. Balance the following equations : (i) (ii) (iii) (vii) (viii) (x) Na + 02 H•202 + 02 Fe + 02 —*Fe203 H20 NH3 + Cuo cu + N2 + + NaOH + NazS04 HNOS + —+ + H20 NaOH + H2S04 _+ NazS04 + H20 BaC12 + H2S04 —+ Basoa + HCI 16. Fill in the following blanks with suitable words : (n) Chemical equations are balanced to satisfy the law Of „ (b) A solution made in water is known as an solution and indicated by the symbol

 

Short Answer Type Questions 17. (a) Give One example Of a chemical reaction. (b) State two characteristics Of the chemical reaction which takes place when dilute sulphuric acid is poured over zinc granules. (c) Give two characteristics Of the chemical reaction which cxcurs on adding potassium iodide solution to lead nitrate solution. IS. (a) What is a chemical equation ? Explain with the help Of an example. (b) Giving examples, State the difference between balanced and unbalanced chemical equations. (c) Balance the following chemical equations : ( i) NH3 N2 + (ii) C + C02 _+ CO 19. When hydrogen is passed over copper oxide, copper and steam are formed. Write a balanced equation for this reaction and State which Of the chemicals are : (i) elements compounds (iii) reactan ts (it') produce; (v) metals (Vi) non-metals 20. (a) What are the various ways in which a chemical equation can be made more informative ? Give examples to illustrate your answer. (b) Write balanced chemical equation from the following information : An aqueous calcium hydroxide solution (lime water) reacts with carbon dioxide gas to produce a solid calcium carbonate precipitate and water. 21. (a) What is a balanced chemical equation ? Why should chemical equations be balanced ? (b) Aluminium burns in chlorine to form aluminium chloride (AIC13). Write a balanced chemical equation for this reaction.

 

20 SCIENCE FOR TENTH CLASS : CHEMISTRY (c) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas. Write a balanced chemical equation for this reaction. 22. (n) Explain, with example, how the physical States Of the reactants and products can be shown in a chemical equa tion. (b) Balance the following equation and add State symbols : Zn + MCI znC12 + H2 (c) Convey the following information in the form Of a balanced chemical equation : "An aqueous solution Of ferrous sulphate reacts with an aqueous solution Of sodium hydroxide to form a precipitate Of ferrous hydroxide and sodium sulphate remains in solution." 23. Write any two observations in an activity which may Suggest that a chemical reaction has taken place. Give an example in support Of your answer. 24. (a) Aluminium hydroxide reacts with sulphuric acid to form aluminium sulphate and water. Write a balanced equation for this reaction. (b) Balance the following chemical equation : Mn02 + HCI—» MnC12 + + 1-120 25. Write the balanced equations for the following reactions, and add the State symbols : (n) Magnesium carbonate reacts with hydrochloric acid to produce magnesium chloride, carbon dioxide and wa ter. (b) Sodium hydroxide reacts with sulphuric acid to produce sodium sulphate and water. 26. Carbon monoxide reacts with hydrogen under certain conditions to form methanol (CH30H). Write a balanced chemical equation for this reaction indicating the physical States Of reactants and product as well as the conditions under which this reaction takes place. 27. (a) Potassium chlorate (KC103) on heating forms potassium chloride and oxygen. Write a balanced equation for this reaction and indicate the evolution Of gas. (b) Rewrite the following information in the form Of a balanced chemical equation : Magnesium burns in carbon dioxide to form magnesium oxide and carbon. 28. (a) Substitute formulae for names and balance the following equation : Calcium carbonate reacts with hydrochloric acid to produce calcium chloride, water and carbon dioxide (b) Write balanced chemical equation with State symbols for the following reaction : Sodium hydroxide solution reacts with hydrochloric acid solution to produce sodium chloride solution and water.

 

29. 30. 31. 32. Ammonia reacts with oxygen to form nitrogen and water. Write a balanced chemical equation for this reaction. Add the State symbols for all the reactants and products. Write a balanced chemical equation for the process Of giving the physical States Of all the substances involved and the conditions Of the reaction. Translate the following statement into chemical equation and then balance it : Barium chloride solution reacts with aluminium sulphate solution to form a precipitate Of barium sulphate and aluminium chloride solution. When potassium nitrate is heated, it decomposes into potassium nitrite and oxygen. Write a balanced equation for this reaction and add the State symbols Of the reactants and products. Long Answer Type Questions 33. (n) What is meant by a chemical reaction ? Explain with the help Of an example. (b) Give one example each Of a chemical reaction characterised by : (i) (ii) (iii) (v) evolution Of a gas change in colour formation Of a precipitate change in temperature change in State.

 

CHEMICAL REACTIONS AND EQUATIONS 34. (a) State the various characteristics Of chemical reactions. (b) State one characteristic each Of the chemical reaction which takes place when : (i) dilute hydrochloric acid is added to sodium carbonate (ii) lemon juice is added gradually to potassium permanganate solution (iii) dilute sulphuric acid is added to barium chloride solution (iv) quicklime is treated with water (v) wax is burned in the form Of a candle 35. (a) What do you understand by exothermic and endothermic reactions ? (b) Give one example Of an exothermic reaction and one Of an endothermic reaction. (c) Which Of the following are endothermic reactions and which are exothermic reactions ? 21 (i) Burning Of natural gas (iii) Electrolysis Of water (v) Decomposition Of calcium carbonate (ii) Photosynthesis (it') Respiration

 

Multiple Choice Questions (MCQs) 36. 37. 38. 39. 40. 41. One Of the following not happen during a chemical reaction. This is : (n) Breaking Of Old chemical bonds and formation Of new chemical bonds (b) Formation Of new substances with entirely different properties (c) Atoms Of one element change into those Of another element to form new products. (d) A rearrangement Of atoms takes place to form new products. Which Of the following does not involve a chemical reaction ? (n) digestion Of food in Our body (b) process Of respiration (c) burning Of candle wax when heated (d) melting Of candle wax on heating You are given the solution Of lead nitrate. In order to obtain a yellow precipitate you should mix with it a solution Of : (n) potassium chloride (c) potassium sulphide (b) potassium nitride (d) potassium iodide An acid which can decolourise purple coloured potassium permanganate solution is : (n) sulphuric acid (c) carbonic acid (b) citric acid (d) hydrochloric acid The chemical reaction between two substances is characterised by a change in colour from orange to green. These two substances are most likely to be : (n) potassium dichromate solution and sulphur dioxide (b) potassium permanganate solution and sulphur dioxide (c) potassium permanganate solution and lemon juice (d) potassium dichromate solution and carbon dioxide. The chemical reaction between quicklime and water is characterised by : (n) evolution Of hydrogen gas (b) formation Of slaked lime precipitate (C) change in temperature Of mixture (d) change in colour Of the product

 

42. One Of the following is an endothermic reaction. This is : (n) combination Of carbon and Oxygen to form carbon monoxide (b) combination Of nitrogen and oxygen to form nitrogen monoxide (c) combination Of glucose and oxygen to form carbon dioxide and water (d) combination Of zinc and hydrochloric acid to form zinc chloride and hydrogen 43. Which Of the following is not an endothermic reaction ? (a) Cacog cao + C02

 

22 SCIENCE FOR TENTH CLASS : CHEMISTRY (b)2H20 2H2 + 02 (c) C02 + C6H1206 + 602 (d) + 602 C02 + 61120 44. One Of the following is an exothermic reaction. This is : (n) electrolysis Of water (b) conversion Of limestone into quicklime (c) process Of respiration (d) prcxess Of photosynthesis 45. The chemical equations are balanced to satisfy one Of the following laws in chemical reactions. This law is known as : (n) law Of conservation Of momentum (b) law Of conservation Of mass (c) law Of conservation Of motion (d) law Of conservation Of magnetism

 

 

 

 

 

 

 


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