Correct option is D
Law of Octaves:
The law of octaves was proposed by John Newlands in 1865.
He observed that when elements are arranged in increasing order of their atomic weights, every eighth element has similar properties, like musical notes repeating every eighth note.
Applicability:
The law of octaves was applicable only up to Calcium (Ca) (atomic number 20).
Beyond calcium, the properties of elements did not match the periodic pattern due to the presence of transition elements and inconsistencies in atomic weights.
