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OXFORD HIGH SCHOOL, HOWRAH - 09 Pre - ICSE Examination 2020-2021 Subject - Chemistry Science paper - 2 Time:( Two hours ) F.M - 80 Question 1: a) Choose the correct answer from the options given below: (10) (i) An element with the atomic number 19willmost likely combine chemically with the element whose atomic number is : (A) 17 (B) 11 (C) 18 (D) 20 (ii) The two main metals in bronze are : (A) Copper and zinc (B) Copper and lead (C) Copper and nickel (iii) The particles present in strong electrolytes are: Only molecules (B) mainly ions (C) ions and molecules (D) only atoms (iv) The aim of Fountain Experiment is to prove that: (A) HCl turns blue litmus red (B) HCl is denser than air (C) HCl is highly soluble in water (D) HCl fumes in moist air (v) Which of the following does not represent oxidation? (A) Loss of electrons (C) Increase in oxidation number (B) Addition of oxygen (D) Addition of hydrogen (D)Copper and tin (vi) Which of the following is a tribasic acid ? (A) Hydrochloric acid (B) Sulphuric acid (C) Phosphoric acid (d) Nitric acid (vii) Hydroxide sparingly soluble in water is : (A)Magnesium Hydroxide (B) Ferrous hydroxide (C) Ferric hydroxide (D) Calcium hydroxide (viii) Pure metal is made --------- during electro refining : Cathode (B) Anode (c) Electrolysis (D) None of these (ix) Ammonium hydroxide will produce a reddish brown precipitate when added to a solution of: (A)CuSO4 (B) Zn(NO3)2 (C) FeSO4 (D) FeCl3 (x) The element with the highest ionization potential in the periodic table is : (A) He (B)Ne (C) Ar (D) Xe (b)The atoms A and B have electronic configuration (2,8,18,2) and (2,6) respectively. (5) Answer the following questions : (i) Which atom is likely to form anion? (ii) What is the atomic number of A ? (iii) What will be the valency of A? (iv) What is the formula of the compound A and B ? (v) Will the compound formed have a high or low melting point ? c) Write IUPAC name and functional group: (i) (ii) (5) CH3---CH2----CH----COOH CH3 H C=C CH2 CH3 H H (iii) CH3---CH2---CH---CH3 OH (iv) CH3-CH-CH2-CH2Br (v) CH3-CH2-CH2CH2CH2CHO CH3 contd... d) (i) Draw the structures of isomers of pentane. (ii) Give the IUPAC name of the isomers of pentane which has branched chain. (e) Write balanced chemical equations for the conversions A to E A Mg B (3+2=5) (5) C MgO Mg(NO3)2 D Mg(OH)2 E MgCO3 (f) Match the elements ( fluorine, hydrogen, chlorine, francium and sodium) with each of the following: (5) (i) The second last element of the period 3. (ii) The element which has the highest electronegativity. (iii) The element which may be placed in group 1 but is not a metal . (iv) The element which has the highest electropositivity. (v) The most metallic element in period 3. (g) State one relevant observation for each of the following: (5) (i) Action of dilute hydrogen chloride on lead nitrate solution. (ii) Reaction of ammonia with heated yellow lead oxide. (iii) When ammonium hydroxide solution is added to a solution of Iron (III)chloride. (iv) Action of dilute sulphuric acid on barium chloride. (v) When acetic acid and ethyl alcohol reacts in presence of sulphuric acid. SECTION II (40 Marks) Attempt any four questions from this section Question 2: (a) Draw the structural formula and identify the functional group: (4) (i) propan-2-ol (ii) Ethanal (iii) But-2-yne (iv) 3 chloro pentene (b) State the observations at the anode and at the cathode when the following are electrolysed. (i) Aqueous copper sulphate between copper electrodes. (ii) Water acidified with sulphuric acid using platinum electrodes. (4) (c) Answer the following questions: (2) (i) What is the pH value of a basic solution? (ii) Name a gas which has rotten egg smell. Question 3: (a) What happens when ( give balanced equations ): (4) (i) Ethylene is burnt in an excess of oxygen. (ii) Ethylene reacts with chlorine. (iii) A mixture of ethylene and hydrogen is passed over nickel at 150 0 C. (iv) Methane reacts with chlorine. contd... (b) (i) Calculate the percentage of water in CuSO4. 5H2O. [ Cu = 63.5 , S = 32, O = 16, H = 1] (2+1=3) (ii) The vapour density of chlorine is 35.5. What is its molecular weight? (c) Explain the following: (3) (i) The wooden shelves on which concentrated sulphuric acid is kept are stained black. (ii) In the manufacture of sulphuric acid , sulphur dioxide is disssolved in conc. H 2SO4 and not in water. (iii) Red colour of bromine disappears when ethene is passed through it? Question 4: (a) Match the following: Column A (i) Reddish brown precipitate (ii) Irritating, pungent smell (iii) Dirty green precipitate (iv) Acid salt (v) Normal salt (5) Column B (a)Ferrous hydroxide (b) Ferric hydroxide (c) Sodium hydrogen carbonate (d) Sodium carbonate (e) Hydrochloric acid (b) A compound on analysis gave the following percentage composition , Na = 29.1, S = 40.5, O = 30.4. If the molecular weight of the compound is 158, find its molecular formula . ( Na = 23, S = 32, O = 16) (3) (c) (i) Give the equation for laboratory preparation of nitric acid. (ii) How is the acid collected in the laboratory? (2) Question 5: (a) Name the terms defined as follows : (5) (i) The process in which an atom or an ion loses electrons. (ii) The process in which carbon atoms share electrons with one another to form long chains. (iii) A salt in which hydrogen of an acid has been wholly replaced by a metal. (iv) The number of protons in the nucleus of an atom. (v) A hydrocarbon with double or triple bonds. (b) The following table represents the first three periods of modern periodic table. (5) These letters are not the symbols for the element concerned. 1 2 13 14 15 16 17 18 X M L P Y Q Z R (i) Give the letter of the most metallic element. (ii) Give the letter of most reactive element. (iii) Where will you find the smallest element? (iv) Name the family of elements represented by elements L, Q, R. (v) What will be the valency of M? contd... Question 6: (a) The following questions refer to the periodic table: (4) (i) Name the first and last element in period 2. (ii) What happens to the atomic size of elements moving from top to bottom of a group? (iii) Which of the elements has the greatest electron affinity among the halogens? (iv) What is the common feature of the electronic configuration of the elements in group 17? (b) A copper mug to be electroplated with silver . (6) (i) Name the electrolyte used in this process. (ii) Name the cathode and anode used during electroplating of silver. (iii) Give the reactions at cathode and anode. (iv) The overall strength of silver ions remain constant in the reaction. Why? (v) State one condition to ensure that the deposit is smooth, firm and long lasting. Question 7: (a) The following questions are relevant to the extraction of aluminium: (4) (i) State the reason for addition of caustic alkali to bauxite ore during purification of bauxite? (ii) Give a balanced equation for the above reaction. (iii) Along with cryolite and alumina another substance is also added to the mixture. Name the substance and give one reason for addition. (b) Explain why : (2+2=4 ) (i) In the electrolysis of alumina using Hall Heroult's process , the electrolyte is covered with powdered coke. (ii) It is necessary to renew the anode periodically. (c) Fill in the blanks: (1+1=2) (i) Metal atoms tend to have a maximum of ------ electrons in the outer most energy level. (ii) Non-metallic elements tend to be ----- conductors of heat and electricity.
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