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MADHUSTHALI VIDYAPEETH F.M 80 Time 2 Hrs ANNUAL EXAMINATION 2018-2019 SUBJECT: CHEMISTRY CLASS- VIII Answers to this Paper must be written on the paper provided separately. You will not be allowed to write during the first 15 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. Section I is compulsory. Attempt 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. Question 1 a) Fill in the blanks: i. is formed when carbon is burnt in a limited supply of air or oxygen. ii. is formed when charcoal is burnt in a limited supply of air. iii. The sticky substance formed when soap is added to hard water iv. Freezing mixture contains and v. An ion which has a positive charge is called a [5] b) Choose the correct alternative: [5] i. In combined state, carbon occurs as (diamond/petroleum) ii. The process by which decayed plants slowly convert into coal is called (carbonistaion/fermentation). iii. Temporary hardness of water can be removed by (filtering/loading). iv. Colloids have the particle size range between (10-7 to 10-10m / 10-10 to 10-12m). v. The sub-atomic particle with positive charge is(proton/neutron). c) Write True/False and rewrite the corrected statement: i. Coke is obtained by destructive distillation of sugar. ii. Coal gas is used in the preparation of artificial fertilizers. iii. Diamond is insoluble in all solvents. iv. Central part of an atom is nucleus. v. Graphite has layers of hexagonal carbon bondings. [5] d) Write the molecular formula for the compounds: i. Baking Soda ii. Sulphuric Acid iii. Ethene iv. Lead (II) Oxide v. Magnesium Carbonate [5] e) What do you observe when: i. Blue vitriol is heated. ii. Blue litmus solution added to water. iii. A lit splinter is introduced into a jar containing carbon dioxide. [5] This paper consists of 3 printed pages. iv. v. Moist blue litmus paper is placed in a jar containing carbon dioxide. A baking mixture containing baking powder is heated. f) Suggest a suitable technique to separate the constituents of the following mixtures: i. Chalk powder from water. ii. Iron from sulphur. iii. Water and alcohol. iv. Sodium chloride and Potassium Nitrate. v. Calcium carbonate and Sodium chloride [5] g) Give one word for the following: i. A liquid non-metal. ii. A soft metal. iii. Substance causing temporary hardness. iv. A mixture of Carbon monoxide and Hydrogen. v. A greyish-black non-metal, a good conductor of electricity. vi. A mixture of metallic oxides. vii. A deliquescent substance. viii. An efflorescent substance. ix. Electrons present in outermost shell. x. A solvent of Iodine. [10] SECTION II (40 Marks) Attempt any four Questions from this Section Question 2 [3+3+4=10] a) Distinguish between homogenous and heterogenous mixture. Write the chemical name of: (i) Vinegar (ii) Marble b) Define mixture. Why is it necessary to separate the constituents of mixture? c) What is chromatography? For which type of mixture is it used. Write an application of chromatography. Question 3 [3+3+4=10] a) Name three fundamental particles of an atom. Give the symbol and charge on each particle. b) Define: (i) Variable valency (ii) Isotopes (iii)Nucleons c) State the mass number, atomic number, number of neutrons and structural diagram of: 12 i. 6 27 ii. 13 Question 4 [3+3+4=10] a) Give the symbol and valencies of: i. Hydroxide ii. Chloride iii. Carbonate b) What is a chemical equation? Why is it necessary to balance a chemical equation? What are the limitations of a chemical equation? c) Write balanced chemical equations: i. Iron + Chlorine Iron(III) Chloride ii. Magnesium + dil. Sulphuric acid Magnesium Sulphate + Water iii. Zinc + Hydrochloric acid Zinc Chloride + Hydrogen iv. Calcium Oxide + Water Calcium Hydroxide 2 Question 5 a) Give reasons: i. Sea water does not freeze at 00C. ii. Alcohol is mixed with water and is used in car radiators. iii. Ice bergs float on ocean water. b) Differentiate between solution, colloid and suspension. c) Suggest one method for removal along with the reactions for: i. Temporary hardness ii. Permanent hardness [3+3+4=10] Question 6 [3+3+4=10] a) Write the balanced chemical equations for the preparation of carbon dioxide by: i. Heating Calcium carbonate. ii. Action of acetic acid on sodium bicarbonate. iii. Action of dil. Sulphuric acid on sodium bicarbonate. b) With reference to the laboratory preparation of carbon dioxide gas, answer these questions: i. Name the chemicals required. ii. How will you collect the gas? iii. Write the balanced equation for the above reaction. iv. Why is sulphuric acid not used for the preparation? c) How is Carbon monoxide gas formed? Write balanced chemical equation: i. CuO + CO ii. Fe2O3 + CO 3
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