WBCS Preliminary Examination 2023 — General Studies · Question 179 of 200

Answer: (B) Magnesium

Newlands (1865) arranged the elements in order of increasing atomic mass and found that every eighth element resembled the first, like the eighth note of a musical octave. His rows ran Li, Be, B, C, N, O, F and then Na, Mg, Al, Si, P, S, Cl, so beryllium falls with magnesium (and lithium with sodium). Calcium comes one octave further on, aluminium is beryllium's diagonal relative in the modern table and sodium pairs with lithium. The law held only up to calcium. Timeline: Dobereiner's triads (1817), Newlands' octaves (1865), Mendeleev's table (1869) and Moseley's modern periodic law based on atomic number (1913).