In which musical note did Newland put the metals Co and Ni with halogens?

Correct — C. In Newlands' Law of Octaves the columns were named after the notes of the musical scale — sa, re, ga, ma, pa, dha, ni, written in Western notation as do, re, mi, fa, sol, la, si.

The first note, do, holds hydrogen, fluorine, chlorine, then cobalt and nickel crammed into a single slot, then bromine, palladium, iodine and platinum with iridium.

So Co and Ni share their note with the halogens F, Cl, Br and I, which is option (c). That placement is one of the standard criticisms of the table: two metals sitting in the halogen column.

Why the others are wrong

• (a)
  Re — Re carries the alkali-metal line — lithium, sodium, potassium, then copper, rubidium and silver. Cobalt and nickel do not appear there.
• (b)
  Mi — Mi, the note ga, holds beryllium, magnesium, calcium, zinc and strontium — the alkaline earths and their neighbours, with no halogen in sight.
• (d)
  Fa — Fa, the note ma, begins with boron and aluminium and runs on through chromium and yttrium. It is the boron-group line, well away from cobalt and nickel.

John Newlands arranged the known elements in increasing order of atomic mass in 1866 and found that every eighth element repeated the properties of the first, like the eighth note of a musical octave. He called it the Law of Octaves and labelled the columns with the notes of the scale.

The idea worked as far as calcium and then broke down. Newly found elements had to be forced in, cobalt and nickel were squeezed into one slot with the halogens, and iron — chemically close to cobalt and nickel — ended up in a different note altogether.

Key facts

• Newlands proposed the Law of Octaves in 1866, arranging elements by increasing atomic mass.
• In Newlands' table cobalt and nickel share the first note with fluorine, chlorine, bromine and iodine.
• The Law of Octaves held only up to calcium.
• Iron was placed away from cobalt and nickel even though the three are chemically similar.

Common traps

• Mapping the Western notes onto the Indian scale the wrong way, when do is sa, mi is ga and fa is ma.
• Remembering only that Co and Ni were badly placed, without remembering which column they landed in.

No directly related past PYQ was found.