Which of the following elements does not form isotopes?

Options

A. Carbon
B. Neon
C. Chlorine
D. Iodine

Explanation

To solve the question of which element does not form isotopes, we will follow these steps:

### Step 1: Understand the concept of isotopes
Isotopes are variants of a particular chemical element that have the same number of protons (atomic number) but different numbers of neutrons, which results in different mass numbers.

### Step 2: Analyze the options
We need to evaluate each of the given elements to determine if they form isotopes.

- **Option A: Carbon (C)**
- Carbon has isotopes, such as Carbon-12, Carbon-13, and Carbon-14. Therefore, it does form isotopes.

- **Option B: Neon (Ne)**
- Neon is a noble gas and is known not to have stable isotopes. It primarily exists as Neon-20, and while there are some unstable isotopes, they are not commonly found in nature. Thus, Neon does not form isotopes in a stable manner.

- **Option C: Chlorine (Cl)**
- Chlorine has isotopes, including Chlorine-35 and Chlorine-37. Therefore, it does form isotopes.

- **Option D: Iodine (I)**
- Iodine also has isotopes, such as Iodine-127 and Iodine-131. Therefore, it does form isotopes.

### Step 3: Conclusion
Based on the analysis, the only element from the options that does not form stable isotopes is **Neon (Ne)**.

### Final Answer
**Neon (Ne)** does not form isotopes.

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