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ON THE WINGS OF EXCELLENCE CYCLE TEST-3 FOR CLASS X (2018-19) SCIENCE PAPER-3 (CHEMISTRY) TIME: 1 HOUR 15 MINUTES F.M: 50 Answer to this paper must be written on the paper provided separately. You will not be allowed to write during the first 10 minutes. This time is to be spent in reading the Question Paper. The time given at the head of this paper is the time allowed for writing the answers. The intended marks for the questions or parts of the questions are given in brackets [ ]. Question 1 (a) Give one test each to distinguish between the following pairs of chemicals: (i) Zinc nitrate solution and calcium nitrate solution. (ii) Sodium nitrate solutions and sodium chloride solutions. (iii) Iron(III) chloride solutions and copper chloride solutions. [6] (b) Three test tubes contain calcium nitrate solution, zinc nitrate solution and lead nitrate solution respectively. Each solution is divided in two portions (i) and (ii) Describe the effect of: (i) Adding sodium hydroxide solution to each portion in turn till it is in excess. (ii) Adding ammonium hydroxide solution to each portion in turn till it is in excess. [2] (c) Give the equations for the action of ZnO, PbO, and Al2O3 with conc. KOH solution. [3] (d) Write your observations as (a) to (j): [5] (i) (ii) (iii) (iv) (v) Test Methyl Orange Phenolphthalein Litmus Add Sodium carbonate Add Ammonium salt Acidic Soln. (a) (b) (c) (d) (e) Alkaline Soln. (f) (g) (h) (i) (j) Question 2 (a) You are provided with the following salts in separate test tubes: (i) FeSO4 (aq) (ii) aqueous Copper sulphate. What will you observe in each salt solution when Sodium hydroxide solution and Ammonium Hydroxide solution is added separately first in small amount then in excess? Support your answer with relevant chemical equations. [4] (b) X is a reddish brown element. When heated with dilute nitric acid, it gives out a colourless gas Y which turns into a reddish-brown gas on coming contact with air. A blue solution of a substance Z is also formed. The crystals of substance Z when heated give out the reddish brown gas along with another gas. A black residue M is left behind. (i) Name the substance X (ii) Write an equation for the reaction of substance X with dilute nitric acid and name the gas Y. (iii) Name the substance Z and M. Write an equation for the action of heat on substance Z [3] CHE/CT-3/2018-19/KSH This question paper consists of 2 printed pages Page 1 (c) A certain crystalline salt substance P is freely soluble in water. The aqueous solution so formed is neutral to litmus .When P is warmed with aqueous caustic soda, a pungent smelling gas Q is evolved. Gas Q is colourless and turns moist red litmus blue and forms dense white fumes with conc. HCl When barium chloride soln. is added to the aq. soln of P a thick white ppt R is formed. R is insoluble both in dil. HCl and HNO3. Identify P,Q,R. Write the equations for the reaction between: (i) P and aqueous caustic soda (ii) Aq.soln. of P and BaCl2 [3] Question 3 (a) Define Gay Lussac s Law. [1] (b) LPG stands for liquefied petroleum gas .Varieties of LPG are marketed including a mixture of propane (60%) and butane (40%).If 10 litres of this mixture is burnt, find the total volume of carbon dioxide added to the atmosphere. Combustion reaction can be represented as: C3H8 + 5O2 3CO2 + 4 H2O 2 C4H10 +13 O2 8CO2 + 10 H2O [3] (c) Calculate the percentage of nitrogen and oxygen in ammonium nitrate [H-1,N-14,O-16] [3] Question 4 (a) What do you mean by Percentage composition? Calculate the % of water of crystallization in FeSO4.7H2O. (F-56,S-32,H-1,O-16). (b) Diammonium hydrogen phosphate (NH4)2HPO4 is an important N-P fertilizer. A farmer is advised to use 25 kg of phosphorus per hectare. If the farmer has 40 hectares of land. Calculate: (i) How much fertilizer should he buy? (ii) How much nitrogen is added to the soil per hectare? (N-14,H-1,P-31,O-16) [3] [4] (c) If 6 litres of hydrogen and 4 litres of chlorine are mixed and exploded and if water id added to the gases formed, find the volume of the residual gas. [2] Question 5 (a) If a crop of wheat removes 40kg of nitrogen per hectare of soil, what mass of the fertilizer urea CO (NH2)2, would be required to replace the nitrogen of a 5 hectare field? (C-12,H-1,O-16,N-14). [3] (b) Calculate the percentage of sodium in sodium aluminium fluoride (Na3 AlF6) correct to the nearest whole number. (F -19, Na - 23, Al - 27) [2] (c) (ii) 560 ml of carbon monoxide is mixed with 500 ml of oxygen and ignited. The chemical equation for the reaction is as follows: 2CO + O2 2CO2 Calculate the volume of oxygen used and carbon dioxide formed in the above CHE/CT-3/2018-19/KSH This question paper consists of 2 printed pages [3] Page 2
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