One of the most important differences in the environmental condition of primitive earth and present - day earth is :

Options

A. There was no water present in primitive earth
B. The primitive earth's atmosphere was of reducing type
C. There was no atmosphere in the primitive earth
D. Hydrogen was present in free state in primitive earth

Answer

To solve the question regarding the most important difference in the environmental conditions of primitive Earth and present-day Earth, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Primitive Earth Conditions**:
- Primitive Earth, which refers to the early stages of our planet's formation, had a very different atmosphere compared to today. It is crucial to identify the components of the atmosphere during that time.

2. **Analyzing the Options**:
- **Option A**: "There was no water present in the primitive earth."
- This statement is incorrect because water vapor was indeed present in the atmosphere.

- **Option B**: "The primitive earth atmosphere was a reducing type."
- This statement is correct. The early atmosphere was rich in reducing gases, which facilitated the formation of organic compounds.

- **Option C**: "There was no atmosphere in the primitive earth."
- This statement is incorrect. Primitive Earth had an atmosphere composed of gases like carbon dioxide, water vapor, and others.

- **Option D**: "Hydrogen was present in free state in primitive earth."
- This statement is also incorrect. Hydrogen was present in compounds, such as hydrogen cyanide, rather than in a free state.

3. **Identifying the Correct Answer**:
- After analyzing all the options, it is evident that the most significant difference is that the primitive Earth atmosphere was a reducing type (Option B). This is a fundamental distinction from the oxidizing atmosphere we have today.

### Conclusion:
The correct answer is **Option B: The primitive earth atmosphere was a reducing type.**

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