Question

The Newland’s law of octaves for the classification of elements was found to be applicable only up to the element ______________________.
A) potassium
B) calcium
C) cobalt
D) phosphorus

Answer 1

As we know that an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. It is the fifth most abundant element in Earth's crust and the third most abundant metal, after iron and aluminium.

Complete answer:
Law of octaves, in chemistry, the generalization made by the English chemist J.A.R. Newland in $1865$ said that, if the chemical elements are arranged according to increasing atomic weight, those with similar physical and chemical properties occur after each interval of seven elements. The law of octaves states that “Every eight element has similar properties when the eighth element, when the elements are arranged in the increasing order of their atomic masses.

Newlands compared the similarity between the elements to the octaves of music, where every eight note is comparable to the first. This was the first attempt at assigning an atomic number to each element. Newland Law of Octaves was not applicable throughout the arrangement. It was applicable only till calcium. Newland’s law of octaves was applicable only to lighter elements having atomic masses up to $40$ u i.e., up to calcium. After calcium, every eighth element did not possess properties similar to that of the first element.

After calcium the mass of the elements increases manifold and hence the eighth element after calcium was not having properties similar to that of calcium. In short, this law resonates with only light elements.
Hence, The Newland’s law of octaves for the classification of elements was found to be applicable only up to calcium.

Therefore, option B is the correct answer.

Note: Newlands assumed that only $56$ elements would exist in nature and believed that no more elements would be discovered. However, Mendeleev left gaps deliberately so that the undiscovered elements could get a place in his periodic table.