Given below are two statements :
Statement I : According to the Law of Octaves, the elements were arranged in the increasing order of their atomic number.
Statement II : Meyer observed a periodically repeated pattern upon plotting physical properties of certain elements against their respective atomic numbers.
In the light of the above statements, choose the correct answer from the options given below :

Solution

Chemistry ma’am · 3 steps

Check the dates: atomic number came only in 1913, long after Newlands and Meyer did their work.

1. Key fact. The idea of atomic number came from Moseley's X-ray work in 1913. Every classification before that, including those of Newlands and Meyer, used atomic weight (atomic mass).

   Scientist	What they did	Actual basis	Statement says
   Newlands (1865)	Law of Octaves: every 8th element repeats the properties of the 1st	increasing atomic weight	atomic number, false
   Lothar Meyer (1869)	Plotted atomic volume, melting point and boiling point and saw a repeating pattern	against atomic weight	atomic number, false
   Moseley (1913)	Showed that properties depend on atomic number	atomic number	not mentioned

2. Spot the swap. Statement II describes Meyer's periodic pattern correctly. It names the wrong x-axis, atomic number instead of atomic weight, and that one word makes it false.
3. So. Statement I and Statement II are both false. The answer is (a).

The idea to keep. Before Moseley (1913), every classification was by atomic weight: Döbereiner, Newlands, Meyer and Mendeleev. Atomic number belongs only to the Modern Periodic Law.

Answer from the NTA final answer key. Solution by PrepWiser.