Which of the following frequencies does not belong to the $FM$ broadcast band (in $,MHz$)?

If the ratio of the maximum and minimum amplitudes of an amplitude modulated wave is $7:3$,then the modulation index is

The layer of the atmosphere which efficiently reflects high frequency waves particularly at night is

An information signal of frequency $10 \text{ kHz}$ is modulated with a carrier wave of frequency $3.61 \text{ MHz}$. The upper sideband and lower sideband frequencies are:

The height of a $TV$ transmitter antenna is $100 \ m$. What is the area covered by the transmitter for broadcasting? $(R = 6.4 \times 10^{6} \ m)$

In an amplitude modulated signal,the maximum amplitude is $15 V$ and the minimum amplitude is $5 V$. The amplitude of the modulating wave will be (in $V$)