If the highest frequency modulating a carrier is $5 \mathrm{kHz},$ then the number of AM broadcast stations accommodated in a $90 \mathrm{kHz}$ bandwidth are _______ .

Choose the incorrect statement(s):

(i) Skywave communication takes place at frequency above approximately $30 \mathrm{MHz}$.

(ii) Amplitude modulated (AM) radio communication is mostly done by ground wave propagation.

(iii) $\mathrm{F}$ layer of ionosphere is mostly responsible for skywave propagation.

(iv) Bandwidth required for transmission of video signal is generally more than audio signal.

In the network shown,