• Fill in the following blanks with suitable words: (a) The basis for modern periodic table is . (b) The horizontal rows in a periodic table are called . (c) Group 1 elements are called . (d) Group 17 elements are known as . (e) Group 18 elements are called . (f) According to Newlands' classification of elements, the properties of sulphur are similar to those of oxygen because sulphur is the element starting from oxygen.