For which of the following media will the wave propagation occur without experiencing attenuation?

For a radiation of $9 \text{ GHz}$ passing through air,the number of waves passing through $1 \text{ m}$ length is . . . . . . .

The speed of electromagnetic waves is the same for all ........

Given below are two statements:
Statement $I$: Electromagnetic waves are not deflected by electric and magnetic fields.
Statement $II$: The amplitude of the electric field and the magnetic field in electromagnetic waves are related to each other as $E_0 = \sqrt{\frac{\mu_0}{\varepsilon_0}} B_0$.
In the light of the above statements,choose the correct answer from the options given below:

What is the amplitude of the electric field in a parallel beam of light of intensity $\left(\frac{15}{\pi}\right) \text{ W/m}^2$ (in $\text{ N/C}$)? $\left[\text{Assume} \frac{1}{4 \pi \varepsilon_0} = 9 \times 10^9 \text{ Nm}^2/\text{C}^2\right]$

What is the dimension of $\frac{1}{\mu_0 \varepsilon_0}$? ($\mu_0 =$ magnetic permeability and $\varepsilon_0 =$ permittivity of free space)