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ST. JOHN S UNIVERSAL SCHOOL CLASS: X DATE: 12/10/2020 FIRST PRELIMINARY EXAMINATION 2020 2021 CHEMISTRY MARKS: 80 TIMING: 2 Hours Answers to this paper must be written on a ruled sheet. First 15 minutes are to be spent in reading the question paper. The time given at the head of this paper is for writing the paper. The Answer Sheet should have the following details mentioned- Date, Full Name, Class & Division, Subject. The pages should be numbered appropriately. ____________________________________________________________________________________ This Paper comprises of two sections. Section I is compulsory. Attempt any 4 questions from section II. ____________________________________________________________________________________ Section I (40 marks) (Attempt all questions from this section) Question 1 (a) Choose the correct answer from the options given below: [5] (i) Which of the following is an example of an ionic bond: (A) Methane (B) Carbon tetra chloride (C) Water (D) Sodium oxide (ii) Concentrated nitric acid reacts with Sulphur and forms: (A) Phosphoric acid (B) Sulphuric acid (C) Sulphurous acid (D) Hydrochloric acid (iii) Which is a weak electrolyte? (A) Dil. HCl (C) Carbonic acid (B) NaOH (D) KCl (iv) A metal oxide which can react with acid as well as alkali : (A) Silver oxide (B) copper(II) oxide (C) Aluminium oxide (D) Calcium oxide (v) Which of the following gases turns acidified potassium dichromate green: (A) Sulphur dioxide (B) Carbon dioxide (C) Carbon monoxide (D) Chlorine (b) Identify the compound which matches the following description: [5] (i) A compound when heated with copper(II) oxide gives a reddish brown metal. (ii) Oxidised product formed when copper reacts with dilute nitric acid. (iii) An acid that forms curdy white precipitate with silver nitrate. (iv) A compound that dehydrates hydrated copper sulphate . (v) Electrolyte used for electroplating with silver. (c) Write balanced chemical equation for the following reactions: [5] (i) Action of ammonia with nitric acid. (ii) Sodium hydroxide is added to calcium nitrate solution. (iii) Reaction of Dil. HCl and sodium sulphite. (iv) Dilute sulphuric acid reacts with zinc hydroxide. (v) Ammonium hydroxide is added to Iron(II) sulphate solution. (d) State one relevant observation for each of the following reactions. [5] (i) Burning of ammonia in air. (ii) Action of sodium hydroxide on zinc nitrate solution. (iii) Action of dilute hydrochloric acid on magnesium. (iv) Addition of concentrated sulphuric acid to sugar. (v) Addition of excess of ammonium hydroxide to copper sulphate solution. (e) Fill in the blanks with the choices given in brackets: [5] (i) Ammonia reacts with excess chlorine to form _________ ( ammonium chloride/nitrogen/nitrogen trichloride) (ii) The basicity of acetic acid is _________ ( 1,3, 4) (iii) The energy released to add an electron to the outermost shell of an atom is known as ___________ (electron affinity/ electronegativity/ ionisation potential) (iv) A compound that does not have lone pair of electrons is _________ ( water/ ammonia/carbon tetra chloride) (v) The element in period 3 whose electron affinity zero is _________ ( Ne, Ar, Na ) (f) Arrange the following according to the instructions given in brackets. [5] (i) Li, K, Na, H ( decreasing order of ionization potential ) (ii) C, Be, O, B (increasing order of electron affinity) (iii) Ca2+ , Zn2+ , Mg2+, Al3+ (in the order of preferential discharge at the cathode) (iv) Br, F, I, Cl (decreasing order of electronegativity) (v) Carbonic acid, Sodium hydroxide, dilute hydrochloric acid, ammonium hydroxide (decreasing order of pH value) (g) Name the gas that is produced in each of the following cases: (i) Action of concentrated sulphuric acid on sulphur. (ii) Action of dilute hydrochloric acid on sodium carbonate. (iii) Action of concentrated sulphuric acid on common salt. (iv) Action of ammonium chloride and slaked lime. (v) Action of concentrated nitric acid on copper. [5] (h) Match the column A with column B [5] Column A Column B (i) Sodium chloride (a) Increases (ii) Ammonium ion (b) Covalent bond (iii)Electronegativity across the (c) Ionic bond period (iv) Non-metallic character down the (d) Covalent & co-ordinate bond group (v) Methane (e) Decreases Section II (40 Marks) (Attempt any 4 questions from this section) Question 2 (a) Copper sulphate solution is electrolysed using copper electrodes: (i) Write the observation at anode. (ii) Write the reaction at cathode and anode. (b) Identify the anion present in the following compounds: [3] [3] (i) Compound A on heating with copper turning and concentrated sulphuric acid liberates a reddish brown gas. (ii) A compound B on reacting with dilute hydrochloric acid gives a gas that turns lead acetate paper black. (iii) A compound C on reacting with dilute sulphuric acid liberates a gas which turns lime water milky, but the gas has no effect on acidified potassium dichromate solution. (c) Some properties of sulphuric acid are listed below. Choose the property A,B,C or D which is responsible for the reactions (i) to (iv). [4] (A) Acid (B) Non- Volatile acid (C) Oxidising agent (D) Dehydrating agent (i)C + 2H2SO4 CO2 + 2H2O + 2SO2 (ii) C12H22O11 + nH2SO4 12C + 11H2O + nH2SO4 (iii) NaNO3 + H2SO4 NaHSO4 + HNO3 (iv) CuO +H2SO4 CuSO4 + H2O Question 3 (a) Name the following: [3] (i) A normal salt and an acid salt of the same acid. (ii) A salt insoluble in cold water but soluble in hot water. (b) (i) How is hydrochloric acid prepared in the laboratory. (ii) State 2 reasons for the special arrangement. (c) Draw the electron dot diagrams for the formation of : [3] [4] (i) Hydronium ion (ii) Sodium chloride Question 4 (a) Solution A is sodium hydroxide solution. Solution B is a week acid. Solution C is dilute sulphuric acid. Which solution will : [3] (i)Liberate Sulphur dioxide from sodium sulphite. (ii)Gives reddish brown precipitate with ferric chloride solution. (iii)Contains molecules and ions. (b) Electrons are added to an element X. [3] (i) Is X is getting oxidized or reduced ? (ii) What will be the charge of X after the addition of electrons. (iii)Which electrode will X migrate during the process of electrolysis. (c) Answer the following: (i) Name the process by which nitric acid is manufactured. [4] (ii) Write all relevant chemical equations for the above process. Question 5 (a) A person wishes to electroplate an article with nickel. [3] (i) Name the electrolyte. (ii) Name the anode. (iii)Give the reaction at cathode. (b) Identify the cations that shows the following colours for the flame test. [3] (i) Brick red (ii) Lilac (iii)Golden yellow (c) Answer the following based on the first three periods of the modern periodic table. [4] (i) Write the formula of the sulphate of the element with atomic number 13. (ii) What is the electronic configuration of the element in the third period which gains one electron to change into an anion. (iii)What type of bonding will be present in the oxide of the element with atomic number 1. (iv)Name the element that has highest electronegativity. Question 6 (a)Elements- W, X, Y & Z have electronic configurations: W= 2,8,2 ; X= 2, 7 Y = 2,8,5 ; Z = 2,1 [3] (i)Which type of chemical bond is formed between W & X (ii) What is the chemical formula of the compound formed between: (a) X & Z (b) W & Y (b) Pick out the insoluble salts: [3] (i) CaSO4 , MgSO4 , K2SO4 (ii) CuS, Na2S, K2S (iii) AgCl, FeCl3 , CuCl2 (c) The following questions are based on the preparation of ammonia in the laboratory. [4] (i) Explain why ammonium nitrate is not used in the preparation of ammonia. (ii)How is ammonia gas collected. (iii) Explain why it is not collected over water. (iv)Name the drying agent used. Question 7 (a) Distinguish between the following using a chemical test. (i) Ferrous nitrate and lead nitrate ( Using ammonium hydroxide) (ii) Zinc sulphate and zinc chloride. (Using barium chloride) [3] (iii) Calcium nitrate and calcium carbonate ( Using acidified ferrous sulphate) (b) Fill in the blanks with appropriate word in each case. [3] (i) Elements of group 1 are strong _______ (oxidizing agents/reducing agents) (ii) Elements with low electronegativity are _______ (Metals/non-metals) (iii) Atomic size of neon is ________ (more/less) than fluorine. (c) Answer the following questions based on the laboratory preparation of nitric acid. [4] (i) Why concentrate hydrochloric acid is not used. (ii) High temperature is not used. Why (iii) The complete apparatus is made of glass only. Give reason (iv) Concentrated nitric acid appears yellow when it is left standing in glass bottle. Explain.
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