Which frequency of microwave is used by a microwave oven to cook food (in $GHz$)?

Microwaves are used in the following:

The radio waves of frequency $300 \,MHz$ to $3000 \,MHz$ belong to

The correct match between the entries in column $I$ and column $II$ is:
$I$ (Radiation) | $II$ (Wavelength)
$(a)$ Microwave | $(i)$ $100 \, m$
$(b)$ Gamma rays | $(ii)$ $10^{-15} \, m$
$(c)$ $A.M.$ radio waves | $(iii)$ $10^{-10} \, m$
$(d)$ $X$-rays | $(iv)$ $10^{-3} \, m$

If microwaves,$X$ rays,infrared,gamma rays,ultraviolet,radio waves and visible parts of the electromagnetic spectrum are denoted by $M, X, I, G, U, R$ and $V$ respectively,then which of the following is the arrangement in ascending order of wavelength?

If wavelengths of visible rays, microwaves, and $X$-rays are $\lambda_v$, $\lambda_m$, and $\lambda_x$ respectively, then which of the following relations is correct?