Hi, can you help me with this questions. I tried solving using formulas I have learned, but the answer is never correct. help me please.

1)In what range should the inductance of the oscillating loop coil be varied to change the frequency of oscillation from 400 to 500 hertz. The capacity of the capacitor is 10 μF.
2)What size inductance coil should be included in the oscillating circuit at 10 MHz? What to get free swings? The capacity of the capacitor is 50 pF.
3)How many oscillations will be made in an electromagnetic wave with a wavelength of 30 m during one period of a sound wave with a frequency of 200 Hz?
4)What is the impedance of a 4 µF capacitor in a 50 and 400 Hz AC circuit?​