What is the value of the speed of light in free space?

For plane electromagnetic waves propagating in the $z$-direction,which one of the following combinations gives the correct possible direction for $\vec{E}$ and $\vec{B}$ fields respectively?

If the magnetic field of a light wave oscillates parallel to the $y-$ axis and is given by $B_y = B_m \sin(kz - \omega t)$,the direction of wave travel and the axis along which the electric vector oscillates are:

The equation that represents the magnetic field of a plane electromagnetic wave which is propagating along the $x$-direction with a wavelength of $10 \,mm$ and a maximum electric field of $60 \,Vm^{-1}$ in the $y$-direction is (where,$c$ is the speed of light):

Consider an electromagnetic wave propagating in a vacuum. Choose the correct statement.

During the propagation of electromagnetic waves in a medium,