Answer. Aim: To observe what happens when quicklime is added to water taken in a beaker. Materials Required:- Quicklime (calcium oxide), water, beaker.Procedure: 1. Take 5 g of calcium oxide in a beaker. 2. Add water to it slowly. 3. Touch the beaker. 4. Note down the observations. Observation: Calcium oxide reacts with water vigorously to form calcium hydroxide with the evolution of heat. Chemical Reaction: Conclusion: The reaction between CaO (Calcium oxide) and H2O is a combination reaction. It is an exothermic process because heat is evolved.Chemical Reactions and Equations Chapter Wise Important Questions Class 10 Science October 1, 2019 by Bhagya Chemical Reactions and Equations Chapter wise important question for Class 10 Science PDF will help you in scoring more marks.. This consists of 1 mark Questions, 3 Mark Numericals Questions, 5 Marks Numerical Questions and previous year questions from Chemical Reactions and Equations Chapter.Chemical Reactions and Equations Chapter Wise Important Questions Class 10 Science NCERT SolutionsSample PapersNCERT Exemplar SolutionsShort Answer Type Questions[l] [2 Marks] -Year 2015 1.“We need to balance a skeltal chemical equation.” Give reason to justify the statement. Answer. Skeltal chemical equation are unbalanced. We need to balance chemical equation because of law of conservation of mass. It states that ‘matter can neither be created nor be destroyed’. Therefore chemical equation must be balanced in each and every chemical reaction. 2.Giving an example list two information which make a chemical equation more useful (informative). Answer. (i) Physical state of reactants must be mentioned, e.g. 2H2 (g) + O2 (g)——– > 2H20 (l) (ii) Condition in which reaction takes place are written on the arrow head, e.g. Consider the following chemical reaction X + Barium chloride——–> Y + Sodium chloride (White ppt) (a) Identify ‘X’ and ‘Y’ (b) The type of reaction (a) ‘X’ is Na2SO4 and Y is BaSO4. (b) The type of reaction Na2SO4 + BaCl2—–> BaSO4 + 2NaCl (White ppt) The reaction is precipitation reaction. It is also called double displacement reaction.CBSE Class 10 Science – More ResourcesNCERT Solutions for Class 10 ScienceNCERT Exemplar Class 10 ScienceCBSE Class 10 Previous Year Question Papers Class 10 Science Important Questions 4. Name the reducing agent in the following reaction: 3MnO2 + 4Al———— > 3Mn + 2Al2O3 State which is more reactive, Mn or A1 and why? Answer. ‘Al’ is reducing agent. ‘AT is more reactive than Mn v ‘Al’ displaces Mn from its oxide. 5.(i) Write a balanced chemical equation for process of photosynthesis. (ii)When do desert plants take up carbon dioxide and perform photosynthesis? Answer. (ii) In desert plants the stomata are open at night. They take CO2 at night and is stored in the form of acid and is used during day time for photosynthesis.Short Answer Type Questions[ll] [3 Marks] -Year 2015 6.A Name the type of chemical reaction represented by the following equation: Answer. (i) Combination reaction (ii) Double displacement reaction (Precipitation reaction) (iii) Decomposition reaction. 7. Write the chemical equation of the reaction in which the following changes have taken place with an example of each: (i) Change in colour (ii) Change in temperature (iii) Formation of precipitate Answer. (i)Cu (s) + 2AgNO3 (aq)———–> Cu(NO3)2(aq) + 2Ag The solution will become blue in colour and shiny silver metal will be deposited. (ii) NaOH + HCl ———–> NaCl + H2O+ heat The temperature will increase because heat will be evolved. (iii) Pb(NO3)2 (aq) + 2KI (aq)———–> Pbl2 (s) + 2KNO3 (aq) Yellow ppt Yellow precipitate of Pbl2will be formed. 8.State the type of chemical reactions and chemical equations that take place in the following: (i) Magnesium wire is burnt in air. (ii) Electric current is passed through water. (iii) Ammonia and hydrogen chloride gases’are mixed. Answer. 9.(a) Write the essential condition for the following reaction to take place: 2AgBr—-> 2Ag + Br2 Write one application of this reaction. (b) Complete the following chemical equation of a chemical reaction 2FeS04 — (c) What happens when water is added to quick line. Write chemical equation. Answer. This reaction is used in photography. (c) Slaked lime is formed with hissing sound and lot of heat is envolved. 10. 2g of ferrous sulphate crystals are heated in a dry boiling tube. (i) List any two observations. (ii) Name the type of chemical reaction taking place. (iii) ‘Write the chemical equation for the reaction. Answer. (i) •Green colour of Fe SO4 disappears and reddish brown solid is formed. • Smell of burning sulphur. (ii) Decomposition reaction Long Answer Type Questions [5 Marks] -Year 2015 11. (a) Define a balanced chemical equation. Why should an equation be balanced? (b) Write the balanced chemical equation for the following reaction: (i) Phosphorus burns in presence of chlorine to form phosphorus penta chloride. (ii) Burning of natural gas. (iii) The process of respiration. Answer. (a) Balanced chemical equation has an equal number of atoms of different elements in the reactants and products. According to law of conservation of mass, matter can neither be created nor be destroyed in a chemical reaction. (b)(i) P4 (s) + 10Cl2 (g) ———> 4PCl5 (S) (i)CH4 (g) + 2O2 (g) ———> CO2 (g) + 2H2O(l) + heat energy (iii) C6H12O6 (s) + 6O2 (g) + 6H2O ———> 6CO2 (aq) + 12H2O (l) + energy 12.(a) Explain two ways by which food industries prevent rancidity. (b) Discuss the importance of decomposition reaction in metal industry with three points. Answer. (a) (i) Rancidity can be prevented by adding antioxidants to food containing fat and oil, e.g. butylated hydroxy anisole is added to butter as antioxidant. (ii) It can be prevented by packaging fat and oil containing foods in nitrogen gas. (b) (i) Molten NaCl is electrolytically decomposed to form sodium metal. (ii) Aluminium metal is obtained by electric decomposition of bauxite ore mixed with cryolite. (iii) Carbonate ores are thermally decomposed to give metal oxide which on reduction give metal.Short Answer Type Question[I] [2 Marks] -Year 2014 13. What is observed when a solution of potassium iodide solution is added to a solution of lead nitrate? Name the type of reaction. Write a balanced chemical equation to represent the above chemical reaction. Answer.Yellow precipitate of lead iodide is formed. It is precipitation reaction. Pb( NO3)2 (aq) + 2KI (aq) —-> Pbl2 (s) + 2KNO3 (aq) It is also called double displacement reaction.short Answer Type Question[ll] [3 Marks] -Year 2014 14.Write chemical equation reactions taking place when carried out with the help of (a) Iron reacts with steam (b) Magnesium reacts with dil HCl (c) Copper is heated in air. Answer. Long Answer Type Question [5 Marks] -Year 2014 15.(a) Write one example for each of decomposion reaction carried out with help of (i) Electricity (ii) Heat (iii)