Up to which element was the law of octaves found to be applicable?

Correct option is B

The correct answer is (b) Calcium.
· The Law of Octaves was proposed by John Newlands in 1865, an early attempt at organizing the known elements. According to this law, elements were arranged in order of increasing atomic weights, and it was observed that every eighth element had similar properties to the first. This pattern was analogous to the octaves in music, hence the name.
· Newlands' Law of Octaves was found to be applicable and consistent up to the element calcium. After calcium, the properties of the elements did not continue to conform to this pattern, primarily because the heavier elements did not fit into such a simple scheme. This inconsistency highlighted the limitations of the Law of Octaves, leading to its eventual supersession by Dmitri Mendeleev’s periodic table, which arranged elements based on atomic weights but also took into consideration the chemical properties and valence.