Given below are two statements: Statement (I): According to the Law of Octaves, the elements were arranged in the…
Classification of Elements & Periodicity · Class 11 · JEE Main Previous Year Question
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.
(a) Statement I is false but Statement II is true (b) Both Statement I and Statement II are true (c) Statement I is true but Statement II is false (d) Both Statement I and Statement II are false
- a
Statement I is false but Statement II is true
- b
Both Statement I and Statement II are true
- c
Statement I is true but Statement II is false
- d✓
Both Statement I and Statement II are false
Both Statement I and Statement II are false
🧠 Newlands and Meyer both used atomic WEIGHT — not atomic number (which came with Moseley in 1913) Before Moseley's discovery (1913), scientists had no concept of "atomic number." They sorted elements by atomic weight. Any statement attributing "atomic number" ordering to pre-1913 scientists is historically wrong.
🗺️ Check both statements Statement I: Newlands arranged elements in increasing order of atomic number. FALSE. Newlands (Law of Octaves, 1866) arranged elements by increasing atomic WEIGHT, not atomic number.
Statement II: Meyer plotted physical properties against atomic numbers. FALSE. Lothar Meyer plotted properties (like atomic volume) against atomic WEIGHT, not atomic number. Atomic number did not exist as a concept in his time.
Both statements are false.
⚠️ Common mistake Many students accept Statement II as true because Meyer did observe periodicity. He did — but he used atomic WEIGHT, not atomic number. The distinction is important: atomic number came from Moseley's X-ray experiment in 1913.
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