CHEMISTRY SCIENCE Paper - 2 II. ANALYSIS OF PERFORMANCE Question 1 (a) Select from the list the gas that matches the description given in each case: [ammonia, ethane, hydrogen chloride, hydrogen sulphide, ethyne] (i) This gas is used as a reducing agent in reducing copper oxide to copper. (ii) This gas produces dense white fumes with ammonia gas. (iii) This gas is used for welding purposes. (iv) This gas is also a saturated hydrocarbon. (v) This gas has a characteristic rotten egg smell. (b) Choose the most appropriate answer for each of the following: (i) Among the elements given below, the element with the least electronegativity is: (A) Lithium (B) Carbon (C) Boron (D) Fluorine (ii) Identify the statement which does not describe the property of alkenes: (A) (B) (C) (D) They are unsaturated hydrocarbons They decolourise bromine water They can undergo addition as well as substitution reactions They undergo combustion with oxygen forming carbon dioxide and water. (iii) This is not an alloy of copper: (A) Brass (B) Bronze (C) Solder (D) Duralumin. (iv) Bonding in this molecule can be understood to involve coordinate bonding. (A) Carbon tetrachloride (B) Hydrogen (C) Hydrogen chloride (D) Ammonium chloride 155 
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