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 "anodising".

Explanation

a) Because of high reactivity of alkali metals, they are usually kept under kerosene. Alkali metals are placed in group and start from periods 2 to 7.
b] The element with variable valency stored under water is phosphorus. It shows a variable valency of 3 and 5 and is reactive towards air and not water. It is placed in group 15 and period 3 of periodic table. 
c) Carbon forms the basis of organic compounds. It exhibits tetravalency because it has 4 valence electrons. It is placed in group 14 and period 2 of Periodic table. 
  d] Helium is the lightest inert gas with atomic number 2. It is placed in group 18 and period I of the periodic table.
e] Aluminium metal is used to make other elements corrosion resistant by the process of "anodising". The oxide layer is of AI,O,. The atomic number of aluminium is 13 and it is placed in group 13 and period 3 of the periodic table.