Correct Answer: He started with the element having the lowest atomic mass (hydrogen) and ended with thorium which was the 56th element

Solution : The correct option is He started with the element having the lowest atomic mass (hydrogen) and ended with thorium, which was the 56th element.

Newlands' law of octaves, was proposed by John Newlands in 1865. In this law, every eighth element exhibited similar properties, much like the octaves in music. However, this law was limited and not widely accepted because it did not account for all known elements and didn't accurately predict the properties of elements beyond calcium.