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 one by one.

### Step 1: Analyze the first statement
**Statement A:** "Ground wave propagation can be sustained at frequency 500 kilohertz to 1500 kilohertz."
- Ground wave propagation is indeed effective in the frequency range of 530 kHz to 1710 kHz. Therefore, this statement is **true**.

### Step 2: Analyze the second statement
**Statement B:** "Satellite communication is used for frequency above 30 MHz."
- Satellite communication typically operates in frequency ranges well above 30 MHz. For uplink, the frequency range is from 5.925 GHz to 6.425 GHz, and for downlink, it is from 3.7 GHz to 4.2 GHz. Thus, this statement is also **true**.

### Step 3: Analyze the third statement
**Statement C:** "Sky wave propagation is useful in the range of 30 to 40 megahertz."
- Sky wave propagation is effective in the frequency range of 2 MHz to 30 MHz. Therefore, stating that it is useful in the range of 30 to 40 MHz is **incorrect**. This statement is **false**.

### Step 4: Analyze the fourth statement
**Statement D:** "Space wave propagation takes place through the troposphere."
- Space wave propagation does occur in the troposphere, particularly for frequencies above 30 MHz. Therefore, this statement is **true**.

### Conclusion
Based on the analysis, the wrong statement is **Statement C**: "Sky wave propagation is useful in the range of 30 to 40 megahertz."

### Summary of the Answer
The wrong statement is C: "Sky wave propagation is useful in the range of 30 to 40 megahertz."

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