MAHESH TUTORIALS I.C.S.E. GRADE - X (2017-2018) Exam No. : MT/ICSE/SEMI PRELIM - II - SET -A 020 Periodic Table, Chemical bonding, Acid, Bases and Salts, Practical Work, Mole Concept, Electrolysis Chemistry SCIENCE PAPER - 3 (2 hours) Answers to this Paper must be written on the paper provided separately. You will not be allowed to write during the first l5 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. Q.1. Attempt all questions from Section I and any four questions from Section II. The intended marks for questions or parts of questions are given in brackets [ ]. SECTION I (40 Marks) Attempt all questions from this section. (A) Select the correct answer from the choices A, B, C & D in each case : [5] 1. By which of the following method FeCl 3 can be prepared? (A) Simple displacement Precipitation (C) Synthesis (D) Neutralization 2. An element with highest ionisation potential (A) Caesium Fluorine (C) Helium (D) Neon 3. A compound X consists of only molecules. Hence X will have : (A) A crystalline hard structure A low melting point and low boiling point (C) A ionic bond (D) A strong force of attraction between its molecules. 4. The compound which has only molecules in its solution (A) Acidified water Ammonium hydroxide (C) Sugar solution (D) Salt solution Copyright reserved. This Paper consists of 6 printed pages.
... 2... 5. What type of bond is present in PCl 3? (A) Coordinate bond Ionic bond (C) Both covalent & ionic bond (D) Covalent bond Match the following ions in column A with their correct precipitate formed when sodium hydroxide solution is added to the solutions in column B. [5] Column A Column B 1. Pb 2+ a) Reddish brown 2. Fe 2+ b) Pale blue 3. Zn 2+ c) Dirty green 4. Fe 3+ d) Chalky white soluble in excess 5. Cu 2+ e) Gelatinous white soluble in excess. (C) Give the balanced chemical equation with respect to the preparation of salts. [5] 1. Precipitation of silver chloride from silver nitrate. 2. Preparation of ammonium sulphate 3. Reaction of zinc hydroxide with excess of NaOH. 4. Reaction of barium sulphite with dil.hcl. 5. Reaction of silver chloride with NH 4 OH. (D) Name the following with reference to periodic table : [5] 1. Alkali metal in period 2. 2. The charged particles which attract one another to form electrovalent compounds. 3. A mixed acid anhydride. 4. The decomposition of a chemical compound in the aqueous or fused state by the passage of direct electric current. 5. The process by which metals containing impurities are purified electrolytically to give a pure metal. (E) Select the correct anion of a salt from the anions given, which matches with description 1 to 5. [5] A : CO 3 2, B : NO 3 1, C : SO 4 2, D : Cl l, E : S 2 1. The salt soln. reacts with AgNO 3 soln. to give a white ppt. insoluble in dil. HNO 3. 2. The salt soln. reacts with Ba(NO 3 ) 2 soln. to give a white ppt. insoluble in dil. HNO 3. 3. The salt soln. reacts with Ba(NO 3 ) 2 soln. to give a white ppt. soluble in dil. HNO 3 but insoluble in dil. H 2 SO 4. 4. The salt reacts with dil. H 2 SO 4 on heating evolving a gas which turns KMnO 4 soln. pink to colourless. 5. The salt reacts with conc. H 2 SO 4 on heating evolving a coloured gas which turns potassium iodide paper brown.
... 3... (F) Calculate the following : 1. The number of atoms in 10 litres of ammonia [ N = 14, H = 1] [2] 2. A gas cylinder holds 85 g of a gas X. The same cylinder when filled with hydrogen holds 8.5 g of hydrogen under the same condition of temperature and pressure. Calculate the molecular weight of X. [2] 3. State Gay - Lussac s law of combining volumes. [1] (G) Define : [5] 1. Electron affinity. 2. Chemical bond. 3. Efflorescence. 4. Electroplating. 5. Electrolytic dissociation. (H) Give reasons : [5] 1. Can we store CuSO 4 solution in a Zn vessel? Give a reason. 2. Why aluminium is extracted from its oxide by electrolysis and not by reducing agents? 3. NaCl conduct electricity only in molten state. SECTION II (40 Marks) Attempt any four questions from this section. Question 2 (A) A group of elements in the Periodic Table is given below: [5] Beryllium Magnesium Calcium Strontium Barium Radium Answer the following questions in relation to the above group of elements: a) Which element has the most metallic character? b) Which element would be expected to have the highest electronegativity? c) If the electronic configuration of beryllium is (2, 2) how many electrons are there in the outermost shell of calcium? d) The atomic number of calcium is 20. Write the chemical formula of the compound formed when calcium reacts with chlorine. e) State the metallic nature of the elements of group to the left of this group in the Periodic Table. Justify your answer. Why should an article be electroplated? [1]
... 4... (C) Calculate: i) the number of moles ii) the total number of molecules iii) the total number of atoms. iv) the number of hydrogen atoms in 294 g. of sulphuric acid. [H = 1, S = 32, O = 16] [4] Question 3 (A) (i) 450 cm 3 of carbon monoxide and 200 cm 3 of oxygen are mixed together and ignited. Calculate the composition of the resulting mixture. [3] (ii) Name the law on which the above sum is based. [1] Choose the kind of chemical bond from : [3] a. Ionic bond b. Covalent bond c. Ionic and covalent bond present in the compounds given below. (i) CCl 4 (ii) MgO (iii) NH 4 OH (C) Explain the formation of Magnesium chloride with the help of [3] (i) an ionic equation. (ii) electron dot diagram. (iii) atomic or orbital diagram. [Atomic number Mg = 12, Cl = 17] Question 4 (A) State your observations : [5] (1) Copper is heated with concentrated nitric acid in a hard glass test tube. (2) Potassium chloride is introduced to a non - luminous flame. (3) Copper chloride is introduced to a non - luminous flame. (4) Calcium chloride is introduced to a non-luminous flame. (5) When conc. HCl is passed over heated copper oxide. A compound of carbon, hydrogen and oxygen is found to contain 40% of carbon, 6.7% of hydrogen and 53.3% of oxygen. Calculate its empirical formula. If its vapour density is 30, Calculate the molecular formula [C = 12, H = 1, O = 16] [5] Question 5 (A) State which of following salts is an -acid, normal or basic salt. [3] 1. bleaching powder 2. potassium mercuric iodide 3. sodium sulphite 4. sodium hydrogen sulphite
... 5... 5. sodium silver cyanide 6. basic lead nitrate 7. potassium zincate 8. alum 9. calcium bicarbonate 10. basic copper chloride 11. trisodium phosphate Fig. shows the arrangement of apparatus for the electrolysis of water. [5] B C D A (a) What is the solution marked by A? (b) Give the name of electrode marked by D? (c) What are the products marked by B and C? (d) (e) Give the electrolytic reaction occurring in the solution. For the acidification of water which of these is preferred and why? Dilute sulphuric acid or dilute nitric acid. (C) Distinguish between Sodium carbonate and sodium sulphite. [2] Question 6 (A) Write chemical equations for the conversions as shown below with the help of diagram. ZnCO 3 [6] A Zn(NO 3 ) 2 ZnSO 4 (C) Zn(OH) 2 (E) (D) F ZnO Answer the following with respect to electrolysis of aqueous copper sulphate solution using copper electrodes. [4] + Copper cathode Copper anode Copper sulphate (aq.) Using copper electrodes
... 6... (a) (b) (c) Give the electrode reactions. State your observation at cathode and anode. The blue colour of aq. copper sulphate solution remains unchanged during electrolysis using copper electrodes explain. Question 7 (A) The electronic configuration of an element T is 2, 8, 8, 1. [5] (a) What is the group number of T? (b) What is the period number of T? (c) How many valence electrons are there in an atom of T? (d) What is the valency of T? (e) Is it a metal or a non-metal? Explain the formation of sodium chloride with the help of : [3] (i) (ii) an ionic equation. electron dot diagram. (iii) atomic or orbital diagram [Atomic number Na = 11, Cl = 17] (C) Calculate the following : 1. Calculate the volume at s.t.p. occupied by 6.023 10 22 molecules of a gas X. [2] All the Best