Which of the following is an example of Disciflorae?

$A$ projectile is projected with velocity $k v_e$ in the vertically upward direction from the ground into space. ($v_e$ is the escape velocity and $k < 1$). If air resistance is considered to be negligible,then the maximum height from the centre of the Earth to which it can go will be: ($R =$ radius of Earth)

When a certain metallic surface is illuminated with monochromatic light of wavelength $\lambda$,the stopping potential for photoelectric current is $3V_0$. When the same surface is illuminated with light of wavelength $2\lambda$,the stopping potential is $V_0$. The threshold wavelength of this surface for the photoelectric effect is:

In the isoelectronic species,the ionic radii in $\mathring{A}$ of $N^{3-}$,$O^{2-}$,and $F^{-}$ are respectively given by:

The equivalent resistance between $A$ and $B$ is

Who proposed the cell theory for plants?