question_answer 64)

      Properties of the elements are given below. Where would you locate the following elements in the periodic table? (a) A soft metal stored under kerosene. (b) An element with variable (more than one) valency stored under water. (c) An element which is tetravalent and forms the basis of organic chemistry. (d) An element which is an inert gas with atomic number 2. (e) An element whose thin oxide layer is used to make other elements corrosion resistant by the process of '"an odising".

Answer:

                    (a) Alkali metals are soft and reactive towards air and moisture. Therefore, are stored under kerosene, e.g., sodium and potassium. Sodium metal (Na) is placed in group 1and period 3 or potassium metal (K) is placed in group 1 and period 4 (b) Phosphorus shows variable valency of 3 and 5. It is reactive towards air and not to wards water. Therefore, it is stored under water Phosphorus is placed in group 15 and period 3. (c) The element, carbon (C) is tetravalent and is the basis of organic compounds. It is placed in group 14 and period 2. (d) The lightest inert gas wish atomicnumber2 is helium (He). It is placed in group 18 and period 1. (e) The metal whose thin oxide layer (i.e., Al2O3) is used to make other elements corrosion resistant by the process or anodizing s aluminium (Al). It is placed in group 13 and period 3.