Long range radio transmission is possible when the radio waves are reflected from the ionosphere. For this to happen, the frequency of the radio waves must be in the range 8-85 MHz, 1-17 MHz, 80 MHz, 150 kHz.
80 MHz
1 MHz
150 kHz
8 MHz
Solution:
The radiowaves having frequency between 3 MHz to 30 MHz are reflected from ionosphere.