Question 3. If 44.5 grams of calcium oxide is produced, how many grams of calcium carbonate had to decomposez? What changes in the colour of iron nails and copper sulphate solution do you observe after keeping the iron nails dipped in copper sulphate solution for about 3O minutes ? (i) dilute H2SO4 Does carbonic acid, H2CO3, spontaneously decompose? (i) CO2 Hence, it does not react with dilute HCI. (ii) 2Na(s) + 2H4O(l) → 2NaOH(aq), Question 7. (iv) Take two graduated test tubes filled Water with water and invert them over the two carbon electrodes. You heat the CaCO₃ to decompose it into CaO and CO₂ according to the equation: You cool the container and and determine the mass of the container + contents. (ii) Sulphur dioxide (SO2) gas when passed through acidic potassium permanganate solution (purple in colour) turns it colourless because SO2 is a strong reducing agent. (b) Burning of Liquefied Petroleum Gas (LPG) Answer: (b) Water (H2O) as F2 is getting reduced to HF (iv) V2O2 Calcium carbonate decomposes to form calcium oxide and carbon dioxide gas. Question 18. Question 33. Question 6. If manganese dioxide is added, it increases the reaction rate. (ii) Cu(s) + 2AgNO3 (aq) +Cu(NO3)2(aq) + x (s) (i) Pb(NO3)2(aq) + H2SO4 (aq) ➝ PbSO4(s) + 2HNO3 (aq) (c) Heating of an iron rod to red hot H2S is the reducing agent while SO, is the oxidising agent. (ii) x – 2Ag (b) The container becomes hot because a large amount of heat is released during this reaction. Identify the brown gas ‘X’. (iv) Hydrogen (H2 gas burns with a pop sound when a burning candle is brought near it. Question 11. In a common experiment in the general chemistry laboratory, magnesium metal is heated in air to produce MgO. (b) H2O + F2 → HF + HOF Heat the Potassium chlorate until it is in a liquid state. Question 2. (i) Name the substance which is getting oxidised. (iii) CS2 + 3O2 → CO2 + 2SO2 Question 13. (i) Ferrous sulphate is heated. Question 16. (a) On exposure to air, aluminium forms a hard protective layer of aluminium oxide (AI2O3) which prevent further oxidation. How many moles of #N_2# are formed by the decomposition of 2.5 moles of #NaN_3#? Question 23. An example of decomposition would be the breakdown of potassium What mass of copper oxide will result after a #31*g# mass of copper carbonate is subjected to fierce and prolonged heating? Write the equation for the reaction also. Answer: (iii) The reaction of sodium metal is found to be highly explosive. : (iv) H2 is the reducing agent. Therefore, no reaction occurs. Answer: (d) Hydrogen (H2). (iv) Barium chloride reacts with zinc sulphate to give zinc chloride and barium sulphate. Extra Questions for Class 10 Science Chapter 1 Chemical Reactions and Equations with Answers Solutions. Under what conditions do these grapes ferment? Catalyst changes (usually increases but sometimes decreases) the rate of a chemical reaction without itself being consumed in the reaction. (ii) will not take place. What mass of #"calcium oxide"# results from the decomposition of a #200*g# mass of #"calcium carbonate"#? (iii) CuO is the oxidising agent. Question 4. Name the type of chemical reaction represented by the following equation: Question 8. What happens when sodium or potassium are left outside in the open? The characteristic test for Identify X and also write the chemical reactions involved. Answer: What is wrong with the following equation? (ii) Cu + FeSO4 → CuSO4 + Fe (c) Copper sulphate on treatment with potassium iodide precipitates cuprous iodide (Cu2I)2 liberates iodine gas and also forms potassium sulphate. Question 4. When CO2 gas is passed in excess through lime water, milkiness disappears due to formation of soluble calcium hydrogen carbonate. Question 27. Question 11. (a) Evaporation of petrol (iii) Reaction of sodium metal is found to be highly explosive because it is an exothermic reaction. (i) Following are the two observations : When a compound is heated, its atoms move about more vigourously. Oxygen is the only common gas that relights the splinter and hydrogen gas burns with a pop. What analytical techniques use chemical decomposition? The equation where the number of atoms of each element on both sides of a chemical equation is not equal is called a skeletal equation. Decomposition reactions are initiated by the addition of energy. Oxidation reactions are exothermic. (ii) 3BaCl, + AI2(SO2) → 2AICI3 + 3BaSO4 (i) State the two observations made in the experiment. Answer: Mention one use of each product. What occurs during a decomposition reaction? Zinc is above hydrogen whereas copper is below hydrogen in the activity series of metals. Answer: (i) Carbon dioxide (CO2) gas turns lime water milky when passed through it due to the formation of insoluble calcium carbonate. Which type of reaction is #2Cu(NO_3)_2 -> 2CuO + 4NO_2 + O_2#? 2Mg + O2 ➝ 2MgO. Answer: The breaking of chemical bonds requires the addition of energy, usually in the form of heat. What are some examples of decomposition reactions? Answer: What does hydrogen peroxide spontaneously decompose into? (ii) O2 The method that uses sodium chlorate(I) (sodium hypochlorite) is safer than the method that uses potassium manganate(VII), but will not work well if the sodium chlorate(I) (sodium hypochlorite) is an old sample. (c) 2CusO4 + 4KI → Cu2l2 + 2K2SO4 + l2, Question 21. How do you know when a decomposition reaction is complete? (iii) x – (aq); y – (g) Due to its basic character it turns red litmus paper blue when touched with its aqueous solution. Question 14. (b) is exothermic as heat is released in these changes. Question 5. Write a balanced equation for the reaction of NaBr with Cl 2. Is the electrolysis of water a decomposition reaction? How many grams of #CaO# can be formed from the decomposition of 275 g of #CaCO_3#? (b) 3Mg(s) + N2 (g) → Mg3 N2(s) Combination reaction Balance the following chemical reactions : (i) The substance getting oxidised is H2 This is a type of thermal decomposition reaction. Answer: (iii) The evolution of oxygen (O2) gas during a reaction can be confirmed by bringing a burning candle near the mouth of the test tube containing the reaction mixture. What happens when potassium chlorate is heated in presence of MnO2. A sample of solid potassium chlorate is heated strongly for 30 minutes. Question 25. Answer: (d) is endothermic as heat is absorbed in these changes. The decomposition of potassium chlorate (#KClO_3#) is used as a source of oxygen in the laboratory. The first step would be to know the chemical formula/ formula unit for each compound/ molecule. (ii) The chemical equation for the reaction is: (iii) Cl 2 reacts with slaked lime to form bleaching powder. When copper powder is heated in the presence of air, black copper oxide is formed. Answer: Answer: How does this colour change after heating ? Calcium carbonate decomposes to form calcium oxide and carbon dioxide gas. Question 34. Why do fire flies glow at night? X is calcium oxide, also called quick lime. (i) A yellow precipitate of lead iodide (PbI,) is formed. f) Hydrated copper sulphate crystals are strongly heated. 1 answer. If a drop of a solution of sulfur dioxide in ether or alcohol is added to powdered potassium chlorate, the mass explodes [Mellor 2:311. Answer: (iii) Thermal decomposition reaction. Thanks and God Bless. Answer: Redox Reaction: Those reactions in which oxidation and reduction take place simul taneously, are called redox reactons. How can a decomposition reaction be recognized? In this page, you can find CBSE Class 10 Science Chapter 1 Extra Questions and Answers Chemical Reactions and Equations Pdf free download, NCERT Extra Questions for Class 10 Science will make your practice complete. What will happen to the copper coin ? How much potassium chlorate is needed to produce 19.7 mol of oxygen? Iron nails become brownish in colour and the blue colour of copper sulphate solution fades. Answer: What is the difference between the following two types of reactions ? Zn(s) + 2HCl (aq) → ZnCl2(s) + H2 (g). Lead nitrate can be decomposed by heating. Add a few drops Test tube wenn of dilute sulphuric acid to the water in the nows Water vessel. What happens when: solid potassium chlorate is strongly heated? Write the balanced chemical equations for the following reactions : At this point, you know that the decomposition is complete.. Synthesis and Decomposition are inverse reactions. It is a thermal decomposition reaction. What is the role of a catalyst in a chemical reaction ? Potassium chlorate (KClO3) on heating forms potassium chloride and oxygen. (b) Red litmus paper turns blue when touched with aqueous solution of magnesium oxide. (ii) dilute HCI Answer: The new compound formed is copper (II) chloride (CuCl2), which imparts blue-green colour to the solution. Answer: Answer: Zn(s) + H2SO4 (aq) → ZnSO4(aq) + H2(g) Question 16. An example of a synthesis reaction would be the formation of ammonia. (ii) Name the products formed on strongly heating ferrous sulphate crystals. How does magnesium carbonate decompose under heating? (iv) V2O5 + 5Ca → 2V + 5Cao Can sulfuric acid be decomposed by chemical change? Reaction (i) will take place. The equation where the number of atoms of each element on both sides of a chemical equation is not equal is called a skeletal equation. Answer: (i) Na2 SO4 (aq) + BaCl2 (aq) → BaSO4(s) + NaCl (aq) Continue the cycle until there is no further loss of mass on heating. 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