Ozone layer blocks the radiations of wave length:
(1.) less than 3 × 10 − 7 m
(2.)equal to 3 × 10 − 7 m
(3.)more than 3 × 10 − 7 m
(4.)All of the above

Options

A. `"less than" 3xx10^(-7)m`
B. `"equal to" 3xx10^(-7)m`
C. `"more than" 3xx10^(-7)m`
D. All of the above

Answer

To solve the question regarding the wavelengths that the ozone layer blocks, we will analyze the options provided and use our knowledge about the ozone layer's function in blocking harmful radiation.

### Step-by-Step Solution:

1. **Understanding the Ozone Layer's Function**:
The ozone layer is known for its ability to absorb and block harmful ultraviolet (UV) radiation from the sun. It plays a crucial role in protecting living organisms on Earth.

2. **Identifying the Wavelengths Blocked**:
The ozone layer effectively blocks UV radiation with wavelengths shorter than approximately 290 nanometers (nm). This is a critical point because it indicates the threshold below which radiation is absorbed.

3. **Converting Nanometers to Meters**:
To compare the options given in the question, we need to convert 290 nm into meters:
\[ 290 \text{ nm} = 290 \times 10^{-9} \text{ m} = 2.9 \times 10^{-7} \text{ m} \]

4. **Analyzing the Options**:
- **Option (1)**: Less than \(3 \times 10^{-7} \text{ m}\) - This includes wavelengths shorter than 290 nm, which are blocked by the ozone layer.
- **Option (2)**: Equal to \(3 \times 10^{-7} \text{ m}\) - This is at the threshold and is also blocked by the ozone layer.
- **Option (3)**: More than \(3 \times 10^{-7} \text{ m}\) - This includes wavelengths longer than 290 nm, which are not effectively blocked by the ozone layer.
- **Option (4)**: All of the above - This cannot be true since only the first two options are correct regarding the wavelengths blocked.

5. **Conclusion**:
Based on the analysis, the correct answer is:
- **Option (1)**: Less than \(3 \times 10^{-7} \text{ m}\).

### Final Answer:
The ozone layer blocks the radiations of wavelength **less than \(3 \times 10^{-7} \text{ m}\)**.

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