Which one of the following statements is wrong?

Options

A. Ground wave propagation can be sustained at frequencies 500 KHz to 1500 KHz.
B. Satellite communication is useful for the frequencies above 30 MHz.
C. Sky wave propagation is useful in the range of 30 to 40 MHz.
D. Space wave propagation takes place through tropospheric space.

Answer

To determine which statement is wrong among the given options, we will analyze each statement regarding communication systems.

### Step-by-Step Solution:

1. **Analyze Option 1:**
- Statement: "Ground wave propagation can be sustained at frequencies 500 kHz to 1500 kHz."
- Ground waves are typically low-frequency waves and can operate effectively at frequencies below 1500 kHz.
- **Conclusion:** This statement is correct.

2. **Analyze Option 2:**
- Statement: "Satellite communication is useful for frequencies above 30 megahertz."
- Satellite communication primarily utilizes space waves, which operate at higher frequencies, generally above 30 MHz.
- **Conclusion:** This statement is also correct.

3. **Analyze Option 3:**
- Statement: "Sky waves propagation is useful in the range of 30 to 40 megahertz."
- Sky waves typically propagate in the frequency range of 2 to 30 MHz. Therefore, stating that they are useful in the range of 30 to 40 MHz is incorrect.
- **Conclusion:** This statement is wrong.

4. **Analyze Option 4:**
- Statement: "Space wave propagation takes place through tropospheric space."
- Space waves are indeed higher energy waves that can propagate through the tropospheric space.
- **Conclusion:** This statement is correct.

### Final Conclusion:
The wrong statement among the options is **Option 3**, which claims that sky wave propagation is useful in the range of 30 to 40 megahertz.