Which of the following is $NOT$ true for electromagnetic waves?

In a plane electromagnetic wave,the directions of the electric field and magnetic field are represented by $\hat{k}$ and $2\hat{i}-2\hat{j}$,respectively. What is the unit vector along the direction of propagation of the wave?

What are called non-mechanical waves? Give its examples.

In a plane electromagnetic wave,$U_E$ and $U_B$ are the average energy densities of the electric field and magnetic field,respectively. Then,which of the following is the correct option?

The electric field of a plane electromagnetic wave, travelling in an unknown non-magnetic medium is given by, $E_y = 20 \sin(3 \times 10^6 x - 4.5 \times 10^{14} t) \text{ V/m}$ (where $x, t$ and other values are in $S$.$I$. units). The dielectric constant of the medium is . . . . . . . (Speed of light in free space is $c = 3 \times 10^8 \text{ m/s}$)

$A$ plane electromagnetic wave of wave intensity $6 \ W/m^2$ strikes a small mirror of area $40 \ cm^2$,held perpendicular to the approaching wave. The momentum transferred by the wave to the mirror each second will be: