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M.E.C PUBLIC SCHOOL ICSE Yelahanka New Town Bangalore -560064 Preparatory examination 2024 Subject: Chemistry Grade:10 Marks:80 Date : 20/12/2024 Time: 2hours Instructions: Answers to this paper must be written on the paper provided separately. You will not be allowed to write during first 15 minutes. This time is to be spent in reading the question paper. Read all the questions carefully. The time given at the head of this paper is the time allowed for writing the answers. _____________________________________________________________________ Section A is compulsory. Answer any four questions from Section B. The intended marks for questions or parts of questions are given in bracket( ). _____________________________________________________________________ Section A ( 40 Marks) (Answer all questions from this section) 1. Choose the correct answer to the questions from the given options : (Do not copy the question, write the correct answer only) [15] 1. The number of electrons transferred completely from one atom to other is its : (a) Electrovalency. (b) Covalency (c) Both (a) and (b) (d) None of these 2. A compound with low boiling point is: (a) Sodium chloride. (b) Calcium chloride (c) Potassium chloride (d) Carbon tetrachloride 3. If the pH of a solution is 2 , then the solution is a: (a) Strong acid (b) Strong alkali (c)Weak acid (d) Weak alkali 4. The alkali that dissociates only partially in aqueous solution : (a) Lithium hydroxide (b) Calcium hydroxide (c) Potassium hydroxide (d) Sodium hydroxide 5. Hydronium ion is formed when a molecule of water combines with: (a) Hydrogen atom (b) Proton/Hydrogen ion (c) Hydrogen molecule (d) Oxygen atom 6. Cathode is a reducing electrode. Because : (a) It has less number of electrons (b) It has deficiency of electrons (c) Cations gain electrons from cathode (d) Anions lose electrons to cathode 7. Cryolite _______ the electrical conductivity of electrolyte : (a) Increases (b) Decreases (c) Remains same (d) None of these 8. The compound that is not an ore of aluminium : (a) Cryolite (b) Corondum (c) Fluorspar (d) Bauxite 9. The metallic oxide which when reacts with HCl forms salt and water: (a) Carbon monoxide (b) Nitrous oxide (c) Ammonium hydroxide (d) Sodium oxide 10. On passing ammonia gas over heated copper oxide for some time, a reddish brown residue is left behind. What property of ammonia is demonstrated here: (a) Basic property (b) Oxidising property (c) Reducing property (d) Acidic property 11. Assertion A : Dry hydrogen chloride gas is collected by the upward displacement of air. Reason R : Hydrogen chloride gas is lighter than air. (a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true but R is not the correct explanation of A (c) A is true R is false (d) A is false R is true 12. The number of C-H bonds in ethane molecule is : (a) 6 (b) 12 (c) 4 (d) 2 13. Identify the statement that is incorrect about alkanes: (a) They are hydrocarbons (b) There is a single covalent bond between carbon and hydrogen (c) They are unsaturated hydrocarbons with double or triple bonds (d) On complete combustion they produce carbon dioxide and water 14. Assertion A : Ca(OH)2 , when dissociates in water, furnishes two -OH ions.. Reason R : It is a tri- acidic base. (a) Both A and R are true (b) Both A and R are false (c) A is true R is false (d) A is false R is true 15. The organic compound having a triple carbon- carbon covalent bond is (a) C3H4 (b) C3H6 (c) C3H9 (d) C4H10 2. i. The following sketch represents the electroplating of an iron cup with nickel metal. Study the diagram and answer the following questions. [5] (A) During electroplating the iron cup is placed at the cathode. Why? (B) Name the ion that must be present in the electrolyte. (C) Sate one condition that is necessary to ensure that the deposit is smooth, firm and even. (D) Write the reaction taking place at the cathode. (E) What change would you observe at the anode. ii. Match the column I with column II. (a) (b) (c) (d) (e) Column I Aluminium Ammonia Calcination Calcium chloride Carbon tetra chloride (1) (2) (3) (4) (5) Column II Covalent compound Carbonate ore Haber s process Hall Heroult s process Electrovalent compound [5] iii. Complete the following by choosing the correct answers from the bracket. [5] 1. The compound that does not have a lone pair of electrons is ______(water, ammonia, calcium oxide) 2. The basicity of acetic acid is ______(3,1,4). 3. The process of heating the concentrated ore in a limited supply or absence of air is __________( roasting/ calcination) 4. An alkaline gas gives dense white fumes of ________ ( NH4OH/NH4Cl) with hydrogen chloride gas. 5. Ionic compounds are generally insoluble in _________ ( water/organic solvents). iv. Identify the following. [5] 1. The covalent compounds in which the shared pair of electrons are not at equal distance between the two atoms. 2. A salt formed by the complete neutralization of an acid by a base. 3. Unwanted earthy impurities associated with ore. 4. A homogeneous mixture of two or more metals or a metal and a non-metal in a definite proportion in their molten state. 5. An organic compound containing -COOH functional group. v. (a) Draw the structural diagram for the following compounds: (1) 2,-methyl propane (2) Ethanol (3) 2, 3- dimethylbutane (a) Give the IUPAC name of the following organic compounds: (1) [5] (2) Section B (40 Marks) (Answer any 4 questions from this section) 3. (i) Draw the electron dot diagram to show the formation of ammonium ion. [2] (ii) Name the common refrigerant. How does it deplete ozone layer? [2] (iii) Give reasons: [3] (A) Sodium chloride will conduct electricity only in fused or aqueous solution state. (B) In the electroplating of an article with silver, the electrolyte sodium argentocyanide solution is preferred over silver nitrate solution. (C) Although copper is a good conductor of electricity, it is a non- electrolyte. (iv) On the basis of diagram given below, answer the following questions : [3] (A) Out of A and B, which one is cathode and which one is anode? (B) What is the electrolyte in the tank? (C) What material is used for the cathode? 4. (i) State the type of bond in the following compounds : (A) Water (ii). (B) Calcium oxide [2] Out of HCl, HNO3, C2H5OH, C6H12O6, which will show an acidic character and why? [2] (iii) Define ore. Differentiate between the processes roasting and calcination. (iv) Name three different methods used in the concentration of ore or dressing of ore with the principle behind them: [3] 5. (i) (ii) Identify the correct term for the following statements. [2] (A) A method used to collect HCl gas. (B) The experiment used to demonstrate the high solubility of HCl gas. Name the main metals used in making of alloys given below: (a) Duralumin [3] (b) stainless steel [2] (iii) Rohit has solution of X,Y and Z that has pH 2, 7 and 13 respectively. Which solution: [3] (a) Will liberate sulphur dioxide gas when heated with sodium sulphite? (b) Will liberate ammonia gas when reacted with ammonium chloride? (c) Will not have any effect on litmus paper? (iv) Answer the following: [3] (a) Name the process used in the preparation of liquid ammonia. (b) Name the catalyst and the promoter used in the process. (c) How is ammonia separated from unreacted Nitrogen and Hydrogen in the above mentioned process? 6. (i) Define the following terms: (a) Mineral (b) Concentration of ore (ii) (a) What role does flourspar (CaF2) play in the extraction of aluminium? [2] [2] (b) Why is powdered coke sprinkled over electrolytic mixture? (iii) Write balanced chemical equations for each of the following: [3] (a) Action of warm water on AlN (b) Action of HCl with ammonium hydroxide. (c) Laboratory preparation of HCl (iv) Three different electrolytic cells A, B and C are set up in separate circuits. Electrolytic cell A contains sodium chloride solution, and when the circuit is completed , the bulb glow s brightly. Electrolytic cell B contains an acetic acid solution, and in this case, the bulb glows dimly. Electrolytic cell C contains a sugar solution, and the bulb doesn t glow. Give a reason for each of these observations. [3] 7. (i) Give the electron dot structure of the following: (a) (ii) CCl4 [2] (b) CH4 What is the reason behind covalent compounds existing in the form of gases, liquids or soft solids? [2] (iii) Draw a neat labelled diagram for the silver plating on brass article. [3] (iv) Write the balanced chemical equations for the following reactions : [3] (a) Ammonia gas reacts with water (b) Hydrochloric acid reacts with metal like calcium (c) Reaction of hydrochloric acid with silver nitrate. 8. (i) For the electrorefining of copper : [2] (a) What is the cathode amde up of ? (b) Write the reaction that takes place at anode. (ii) What are acidic salts? Give an example with equation for the formation of acidic salt. [2] (iii) What is catenation? What are saturated and unsaturated carbon atoms? Give one example for each. [3] (iv) Complete the following by selecting the correct option from the choices given: [3] (a) pH of acetic acid is greater than dilute sulphuric acid. So acetic acid contains __________ concentration of H+ ions.( greater/same/low) (b) The indicator that doesnot change colour on passage of HCl gas is ________ ( methyl orange/ blue litmus/phenolphthalein) (c) The acid which can not act as an oxidizing agent is _______ (conc.H2SO/Conc.HNO3/conc.HCl) ********
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