The velocity of electromagnetic waves is parallel to which of the following?

An electromagnetic wave is travelling in $x$-direction with electric field vector given by $\vec{E}_{y} = E_{0} \sin(kx - \omega t) \hat{j}$. The correct expression for the magnetic field vector is:

If the magnetic field in a plane electromagnetic wave is given by $\overrightarrow{B} = 3 \times 10^{-8} \sin (1.6 \times 10^{3} x + 48 \times 10^{10} t) \hat{j} \; T$,then what will be the expression for the electric field?

Show that the average value of radiant flux density $S$ over a single period $T$ is given by $S = \frac{1}{2c\mu_0}E_0^2$.

What is the cause of the greenhouse effect?

If the average power per unit area delivered by an electromagnetic wave is $9240 \ W \ m^{-2}$,then the amplitude of the oscillating magnetic field in the $EM$ wave is: (in $\mu T$)