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 differences in environmental conditions between primitive Earth and present-day Earth, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Primitive Earth**:
- Primitive Earth refers to the early stages of our planet, which is believed to have existed around 4.5 billion years ago. The conditions were vastly different from what we experience today.

2. **Atmospheric Composition**:
- The atmosphere of primitive Earth was composed of various gases, including water vapor, carbon dioxide, carbon monoxide, methane, and ammonia. This indicates that there was indeed an atmosphere present.

3. **Type of Atmosphere**:
- The atmosphere of primitive Earth is described as a "reducing atmosphere." This means it was rich in hydrogen and lacked free oxygen, which is a significant difference from the oxidizing atmosphere we have today.

4. **Evaluating the Options**:
- **Option 1**: "There was no water present in the primitive earth." This is incorrect because water vapor was a component of the early atmosphere.
- **Option 2**: "Primitive earth atmosphere was of reducing type." This is correct as it highlights the significant difference in atmospheric composition.
- **Option 3**: "There was no atmosphere in the primitive earth." This is incorrect since there were gases present in the atmosphere.
- **Option 4**: "Hydrogen was present in the free state in primitive earth." This is also incorrect because hydrogen was not found in a free state; it was part of compounds.

5. **Conclusion**:
- The most important difference in the environmental conditions of primitive Earth compared to present-day Earth is that the atmosphere of primitive Earth was of a reducing type (Option 2).

### Final Answer:
The correct answer is **Option 2: Primitive earth atmosphere was of reducing type.**