The discovery of which of the following group of elements gave a death blow to the Newlands Law-

Options

A. Inert gases
B. Alkali metals
C. Transuranic element
D. Halogens

Answer

To solve the question regarding which group of elements gave a death blow to Newlands' Law of Octaves, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Newlands' Law of Octaves**:
- Newlands proposed that when elements are arranged in order of increasing atomic weight, every eighth element has similar properties. He compared this to musical octaves.

2. **Identify the Limitations of Newlands' Law**:
- Newlands' arrangement worked well for the first 56 known elements but failed to accommodate certain groups of elements that did not fit his pattern.

3. **Recognize the Discovery of Inert Gases**:
- The discovery of inert gases (noble gases) such as Helium, Neon, Argon, Krypton, Xenon, and Radon was significant. These gases were not known during Newlands' time.

4. **Analyze the Impact of Inert Gases on Newlands' Law**:
- The inert gases did not fit into the octaves as proposed by Newlands. They have distinct properties that do not align with the periodic properties of the elements arranged by atomic weight.

5. **Conclude the Answer**:
- The discovery of inert gases provided a clear example of elements that could not be placed within the framework of Newlands' Law of Octaves, leading to its failure. Thus, the answer to the question is the group of **Inert Gases**.

### Final Answer:
The discovery of **Inert Gases** gave a death blow to Newlands' Law of Octaves.

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