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PREPARATORY EXAMINATION – 4, GRADE : X SUBJECT : SCIENCE PEN PAPER TEST, MARCH-2022 MARKS : 80, PART : B, CHEMISTRY, I. Four alternatives are given to each of the following incomplete statements/ questions. Only one of them is correct or most appropriate. Choose the correct alternative and write the complete answer along with its alphabet. 2X1 = 2, Which of the following statements about the given reaction are correct?, 3Fe(s) + 4H2O(g) → Fe3O4(s) +4H2(g), i) iron metal is getting oxidized ii) water is getting reduced, iii) water is acting as reducing agent iv) water is acting as oxidising agent, A)(i), (ii) and (iii) B)(iii) and (iv) C)(i), (ii) and (iv) D)(ii) and (iv), 2. The total number of electrons that take part in forming a bond in N2 is, A) 2 B) 4 C) 6 D) 10, II. Answer the following questions. 3X1= 3, Why do silver articles turn black when kept in the open for a few days?, Give one example for hydrated compound with a molecular formula., Why do ionic compounds have very high melting and boiling point?, III. Answer the following questions. 3X2=6, On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite, white precipitate is obtained., Write a balanced chemical equation of the reaction involved, What other name can be given to this precipitation reaction?, Draw the diagram to show HCl solution in water conducts electric current., Write the balanced equations for the reactions of the following:, i)A powder obtained when magnesium ribbon is burnt is mixed with water., ii) When zinc reacts with concentrated nitric acid., IV. Answer the following questions. 3X3= 9, a) ‘Atomic size and metallic nature are vice-versa in the modern periodic table’ Justify the statement., b) Write any three advantages of modern periodic table., 10. Give reason:, Platinum, gold and silver are used to make jewellery., Sodium, potassium and lithium are stored under oil., Aluminium is a highly reactive metal, yet it is used to make utensils for cooking., 11. Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride., Or, How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?, Do basic solutions also have H+(aq) ions? If yes, then why are these basic?, Plaster of Paris should be stored in a moisture-proof container. Explain why?, V. Answer the following questions. 1X5=5, 11. a) What are functional groups? Write the structural formula of the compound obtained when one atom of hydrogen in ‘Propane’ is replaced by— Br and Cl group., b) Draw the structural formula and compare the following organic compounds: cyclohexane and benzene, c) Explain the following versatile nature of carbon, i) catenation ii) Tetravalency, OR, The molecular formula of the first member of a certain group of organic compounds is CH2O (HCHO). Determine the name and the molecular formula of the third member of this group if the members of this group are in homologous series. What is the general name for this group of organic compounds?, In a specific group of unsaturated hydrocarbons, though the ratio of carbon and hydrogen atoms are 1: 2, CH2 is not the first member of those hydrocarbons. What is the reason for this? Write the structural formula of the first member of that hydrocarbon group.