The discovery of isotopes began with the experiments with

Options

A. Xe
B. Kr
C. Ar
D. Ne

Answer

To solve the question regarding the discovery of isotopes, we will follow these steps:

### Step 1: Understand the Concept of Isotopes
Isotopes are defined as atoms of the same element that have the same atomic number but different atomic masses. This means they have the same number of protons but a different number of neutrons.

**Hint:** Recall that isotopes are related to the atomic structure of elements.

### Step 2: Identify the Context of the Discovery
The question asks about the experiments that led to the discovery of isotopes. This historical context is important to pinpoint the correct element.

**Hint:** Think about the early 20th century and the scientists involved in atomic research.

### Step 3: Recall Key Historical Figures and Experiments
In 1912, scientists J.J. Thomson and Francis William Aston conducted experiments that provided evidence for isotopes. They specifically worked with Neon during these experiments.

**Hint:** Remember the names of the scientists who contributed to the discovery of isotopes.

### Step 4: Analyze the Options Given
The options provided are xenon, krypton, argon, and neon. We need to determine which of these elements was involved in the early experiments that led to the discovery of isotopes.

**Hint:** Focus on the element that was mentioned in connection with the experiments conducted by Thomson and Aston.

### Step 5: Conclude with the Correct Answer
Based on the historical context and the experiments conducted, the correct answer is Neon. It was the first element for which isotopes were identified, leading to the discovery of isotopes in stable non-radioactive elements.

**Final Answer:** The discovery of isotopes began with experiments with **Neon** (Option D).

### Summary of Steps:
1. Understand isotopes.
2. Identify the historical context.
3. Recall key figures and their experiments.
4. Analyze the options.
5. Conclude with the correct answer.