All questions of Periodic Classification of Elements for Delhi Police Constable Exam

Law of Octaves
The Law of Octaves was proposed by John Newlands in 1865 as an early attempt to classify the elements.
Key Features of the Law of Octaves:
- Periodic Recurrence: Newlands observed that when elements were arranged in order of increasing atomic weight, every eighth element exhibited similar properties, akin to musical octaves.
- Arrangement of Elements: He organized the known elements into a table, where he grouped them in rows of seven. The element at the start of each row was similar to the one eight places down.
- Limitations: Newlands' classification was limited to the first 56 elements. It failed for heavier elements and did not accommodate noble gases, which were discovered later.
- Historical Significance: Despite its limitations, Newlands' Law of Octaves was a significant step toward the development of the periodic table, influencing future scientists like Mendeleev.
Impact on Chemistry:
- Foundation for Future Discoveries: Newlands' work laid the groundwork for later periodic laws, showing that chemical properties are related to atomic mass.
- Recognition: Initially met with skepticism, Newlands' contributions were eventually recognized, marking an important milestone in the field of chemistry.
Overall, John Newlands' proposal of the Law of Octaves exemplifies early efforts to categorize elements based on their properties, highlighting the evolving nature of scientific understanding in the classification of elements.

Understanding Transition Metals
The transition metals are found in the d-block of the periodic table. This block is characterized by the filling of d-orbitals, which plays a crucial role in the properties of these elements.
Characteristics of Transition Metals
- Location: The d-block consists of groups 3 to 12 in the periodic table.
- Electron Configuration: Transition metals have partially filled d-orbitals, which leads to unique chemical and physical properties.
- Common Properties:
- Variable Oxidation States: Transition metals can lose different numbers of electrons, leading to various oxidation states.
- Formation of Colored Compounds: Many transition metal compounds exhibit vibrant colors due to d-d electron transitions.
- Catalytic Activity: These metals often act as catalysts in various chemical reactions.
- High Melting and Boiling Points: Transition metals generally possess high melting and boiling points due to strong metallic bonding.
Comparison with Other Blocks
- s-block: Contains alkali and alkaline earth metals, which have a different set of properties, primarily characterized by their high reactivity and simple oxidation states.
- p-block: Comprises nonmetals, metalloids, and some post-transition metals, which exhibit diverse behaviors, but lack the typical metallic properties of transition metals.
- f-block: Contains lanthanides and actinides, known for their complex electron configurations and unique properties, but they do not exhibit the same behavior as transition metals.
Conclusion
In summary, the transition metals are specifically located in the d-block of the periodic table, distinguished by their unique electron configurations and a range of physical and chemical properties that set them apart from elements in the s, p, and f-blocks.

Location of Elements in the Periodic Table
The periodic table is organized in a way that reflects the properties of elements based on their atomic number. The bottom right corner of the periodic table typically contains the heaviest noble gases, which are characterized by their full valence electron shells that make them largely inert.

Understanding the Noble Gases
- **Noble Gases**: The elements in this group are known for their lack of reactivity due to their complete outer electron shells. This group includes Helium, Neon, Argon, Krypton, Xenon, and Radon.


Radon - The Element in Question
- **Radon (Rn)**: Radon is located at the bottom right corner of the periodic table in Group 18 (Noble Gases). It has the atomic number 86 and is the heaviest noble gas.
- **Properties**: As a colorless, odorless, and tasteless gas, Radon is radioactive and is produced naturally from the decay of uranium in soil and rocks. Its radioactivity makes it significant in both environmental studies and health assessments.

Why the Other Options Are Incorrect
- **Helium (He)**: Located at the top right corner, Helium has the atomic number 2 and is much lighter than Radon.
- **Neon (Ne)**: Found above Radon, Neon has the atomic number 10 and is also a lighter noble gas.
- **Argon (Ar)**: Positioned above Radon with the atomic number 18, Argon is heavier than Helium and Neon but lighter than Radon.
In conclusion, the correct answer to the question is indeed option 'D', Radon, as it is the element located at the bottom right corner of the periodic table.